private static void AnnotatePdfUsingTemporaryFile()
{
    // create image collection
    Vintasoft.Imaging.ImageCollection images = new Vintasoft.Imaging.ImageCollection();
    // create annotation controller associated with image collection
    Vintasoft.Imaging.Annotation.AnnotationDataController annotations = 
        new Vintasoft.Imaging.Annotation.AnnotationDataController(images);
    // load PDF file into collection
    images.Add("sourcePdfDocument.pdf");

    // get the annotation collection for selected image
    Vintasoft.Imaging.Annotation.AnnotationDataCollection imageAnnotations = annotations[images.Count - 1];
    // create new annotation
    Vintasoft.Imaging.Annotation.RectangleAnnotationData anno = 
        new Vintasoft.Imaging.Annotation.RectangleAnnotationData();
    anno.Size = new System.Drawing.SizeF(300, 300);
    anno.FillBrush = new Vintasoft.Imaging.Annotation.AnnotationSolidBrush(System.Drawing.Color.AliceBlue);
    anno.Location = new System.Drawing.PointF(0, 0);
    // add new annotation into annotation collection
    imageAnnotations.Add(anno);

    Vintasoft.Imaging.Codecs.Encoders.PdfEncoder encoder = 
        new Vintasoft.Imaging.Codecs.Encoders.PdfEncoder();
    // specify that annotations must be saved with image collection
    encoder.AnnotationsFormat = Vintasoft.Imaging.AnnotationsFormat.VintasoftBinary;
    // save image collection synchronously to new file
    images.SaveSync("destPdfDocument.pdf", encoder);
}

Private Shared Sub AnnotatePdfUsingTemporaryFile()
    ' create image collection
    Dim images As New Vintasoft.Imaging.ImageCollection()
    ' create annotation controller associated with image collection
    Dim annotations As New Vintasoft.Imaging.Annotation.AnnotationDataController(images)
    ' load PDF file into collection
    images.Add("sourcePdfDocument.pdf")

    ' get the annotation collection for selected image
    Dim imageAnnotations As Vintasoft.Imaging.Annotation.AnnotationDataCollection = annotations(images.Count - 1)
    ' create new annotation
    Dim anno As New Vintasoft.Imaging.Annotation.RectangleAnnotationData()
    anno.Size = New System.Drawing.SizeF(300, 300)
    anno.FillBrush = New Vintasoft.Imaging.Annotation.AnnotationSolidBrush(System.Drawing.Color.AliceBlue)
    anno.Location = New System.Drawing.PointF(0, 0)
    ' add new annotation into annotation collection
    imageAnnotations.Add(anno)

    Dim encoder As New Vintasoft.Imaging.Codecs.Encoders.PdfEncoder()
    ' specify that annotations must be saved with image collection
    encoder.AnnotationsFormat = Vintasoft.Imaging.AnnotationsFormat.VintasoftBinary
    ' save image collection synchronously to new file
    images.SaveSync("destPdfDocument.pdf", encoder)
End Sub

private static void AnnotatePdfWithoutUsingTemporaryFile()
{
    // open stream of the PDF document
    System.IO.FileStream stream = new System.IO.FileStream(
        "sourcePdfDocument.pdf", System.IO.FileMode.Open);

    // create image collection
    Vintasoft.Imaging.ImageCollection images = new Vintasoft.Imaging.ImageCollection();
    // create annotation controller associated with image collection
    Vintasoft.Imaging.Annotation.AnnotationDataController annotations = 
        new Vintasoft.Imaging.Annotation.AnnotationDataController(images);
    // add images (pages of PDF document) from the stream to the image collection
    images.Add(stream);

    // get annotation collection for selected image
    Vintasoft.Imaging.Annotation.AnnotationDataCollection imageAnnotations = annotations[images.Count - 1];
    // create new annotation
    Vintasoft.Imaging.Annotation.RectangleAnnotationData anno = 
        new Vintasoft.Imaging.Annotation.RectangleAnnotationData();
    anno.Size = new System.Drawing.SizeF(300, 300);
    anno.FillBrush = new Vintasoft.Imaging.Annotation.AnnotationSolidBrush(System.Drawing.Color.AliceBlue);
    anno.Location = new System.Drawing.PointF(0, 0);
    // add new annotation into annotation collection
    imageAnnotations.Add(anno);

    Vintasoft.Imaging.Codecs.Encoders.PdfEncoder encoder = 
        new Vintasoft.Imaging.Codecs.Encoders.PdfEncoder();
    // specify that annotations must be saved with image collection
    encoder.AnnotationsFormat = Vintasoft.Imaging.AnnotationsFormat.VintasoftBinary;
    // specify that image collection must be saved to the source stream
    encoder.SaveAndSwitchSource = true;
    // save image collection synchronously to the source stream (save changes in PDF document)
    images.SaveSync(stream, encoder);

    // close the stream of PDF document
    stream.Close();
}

Private Shared Sub AnnotatePdfWithoutUsingTemporaryFile()
    ' open stream of the PDF document
    Dim stream As New System.IO.FileStream("sourcePdfDocument.pdf", System.IO.FileMode.Open)

    ' create image collection
    Dim images As New Vintasoft.Imaging.ImageCollection()
    ' create annotation controller associated with image collection
    Dim annotations As New Vintasoft.Imaging.Annotation.AnnotationDataController(images)
    ' add images (pages of PDF document) from the stream to the image collection
    images.Add(stream)

    ' get annotation collection for selected image
    Dim imageAnnotations As Vintasoft.Imaging.Annotation.AnnotationDataCollection = annotations(images.Count - 1)
    ' create new annotation
    Dim anno As New Vintasoft.Imaging.Annotation.RectangleAnnotationData()
    anno.Size = New System.Drawing.SizeF(300, 300)
    anno.FillBrush = New Vintasoft.Imaging.Annotation.AnnotationSolidBrush(System.Drawing.Color.AliceBlue)
    anno.Location = New System.Drawing.PointF(0, 0)
    ' add new annotation into annotation collection
    imageAnnotations.Add(anno)

    Dim encoder As New Vintasoft.Imaging.Codecs.Encoders.PdfEncoder()
    ' specify that annotations must be saved with image collection
    encoder.AnnotationsFormat = Vintasoft.Imaging.AnnotationsFormat.VintasoftBinary
    ' specify that image collection must be saved to the source stream
    encoder.SaveAndSwitchSource = True
    ' save image collection synchronously to the source stream (save changes in PDF document)
    images.SaveSync(stream, encoder)

    ' close the stream of PDF document
    stream.Close()
End Sub