PdfAnnotationDataConverterExportToPdfDocumentSigner Method

var rectData = new RectangleData()
{
    Size = new SizeF(123, 345),
    Location = new PointF(123, 321),
    Fill = new AnnotationBrush(Color.FromArgb(255, 64, 128, 255)),
    Outline = new AnnotationPen(Color.FromArgb(255, 128, 128, 128))
};
var polyData = new PolygonData()
{
    Size = new SizeF(100, 200),
    Location = new PointF(10, 11),
    Fill = new AnnotationBrush(Color.FromArgb(255, 64, 128, 255)),
    Outline = new AnnotationPen(Color.FromArgb(255, 128, 128, 128))
};
polyData.Points.AddRange(new[] { new PointF(1, 1), new PointF(50, 50), new PointF(1, 50) });


var collection = new AnnotationDataCollection() { new LayerData() { Items = { rectData, polyData } } };
var dpis = new[] { new Dpi(96, 96, ResolutionUnit.DotsPerInch) };
var signer = new PdfDocumentSigner(pdfStream, null);

PdfAnnotationDataConverter.ExportToPdfDocumentSigner(collection, AnnotationUnit.Pixel, dpis, signer);

signer.AppendChangesFinal(true);