.NET PDF digital signature SDK

using GdPicturePDF gdPicturePDF = new GdPicturePDF();
gdPicturePDF.LoadFromFile(@"C:\temp\source.pdf");
// Set the certificate from a file.
gdPicturePDF.SetSignatureCertificateFromP12(@"C:\temp\certificate.pfx", "nutrient");
// Add additional signature information.
gdPicturePDF.SetSignatureInfo("John Smith", "Confidential", "Vienna (Austria)",
    "john.smith@nutrient.io");
// Set the measurement unit to centimeters.
gdPicturePDF.SetMeasurementUnit(PdfMeasurementUnit.PdfMeasurementUnitCentimeter);
float width = gdPicturePDF.GetPageWidth();
// Select the last page.
gdPicturePDF.SelectPage(gdPicturePDF.GetPageCount());
// Define the signature boundary box position and dimensions.
gdPicturePDF.SetSignaturePos(width - 7, 10, 5, 2);
// Select the text font type.
string fontName = gdPicturePDF.AddTrueTypeFont("Freestyle Script", false, false, false);
// Save the text alignment to center in a variable.
var center = TextAlignment.TextAlignmentCenter;
// Draw the text to the signature boundary box.
gdPicturePDF.SetSignatureText("John Smith", fontName, 12, GdPictureColor.Blue, center, center, true);
// Add an image resource from a file.
string stampImage = gdPicturePDF.AddJpegImageFromFile("C:\temp\source.jpg");
// Draw the image resource to the signature boundary box.
gdPicturePDF.SetSignatureStampImage(stampImage);
// Save the output to a file.
gdPicturePDF.ApplySignature("C:\temp\output.pdf",
    PdfSignatureMode.PdfSignatureModeAdobePPKMS, false);

Using gdPicturePDF As GdPicturePDF = New GdPicturePDF()
    gdPicturePDF.LoadFromFile("C:\temp\source.pdf")
    ' Set the certificate from a file.
    gdPicturePDF.SetSignatureCertificateFromP12("C:\temp\certificate.pfx", "nutrient")
    ' Add additional signature information.
    gdPicturePDF.SetSignatureInfo("John Smith", "Confidential", "Vienna (Austria)", "john.smith@nutrient.io")
    ' Set the measurement unit to centimeters.
    gdPicturePDF.SetMeasurementUnit(PdfMeasurementUnit.PdfMeasurementUnitCentimeter)
    Dim width As Single = gdPicturePDF.GetPageWidth()
    ' Select the last page.
    gdPicturePDF.SelectPage(gdPicturePDF.GetPageCount())
    ' Define the signature boundary box position and dimensions.
    gdPicturePDF.SetSignaturePos(width - 7, 10, 5, 2)
    ' Select the text font type.
    Dim fontName As String = gdPicturePDF.AddTrueTypeFont("Freestyle Script", False, False, False)
    ' Save the text alignment to center in a variable.
    Dim center = TextAlignment.TextAlignmentCenter
    ' Draw the text to the signature boundary box.
    gdPicturePDF.SetSignatureText("John Smith", fontName, 12, GdPictureColor.Blue, center, center, True)
    ' Add an image resource from a file.
    Dim stampImage As String = gdPicturePDF.AddJpegImageFromFile("C:\temp\source.jpg")
    ' Draw the image resource to the signature boundary box.
    gdPicturePDF.SetSignatureStampImage(stampImage)
    ' Save the output to a file.
    gdPicturePDF.ApplySignature("C:\temp\output.pdf",
        PdfSignatureMode.PdfSignatureModeAdobePPKMS, False)
End Using