Add Digital Signatures to PPTX File

using (Signature signature = new Signature("sample.pdf"))
{
    // initialize digital option with certificate file path
    DigitalSignOptions options = new DigitalSignOptions("certificate.pfx")
    {
        // certifiate password
        Password = "1234567890",
        // digital certificate details
        Reason = "Sign",
        Contact = "JohnSmith",
        Location = "Office1",
        // image as digital certificate appearance on document pages
        ImageFilePath = "sample.jpg",
        //
        AllPages = true,
        Width = 80,
        Height = 60,
        VerticalAlignment = VerticalAlignment.Bottom,
        HorizontalAlignment = HorizontalAlignment.Right,
        Margin = new Padding() {  Bottom = 10, Right = 10},
    };
    signature.Sign("signed.pptx", options);
}