Verifying Text signatures in advance

using (Signature signature = new Signature("signedSample.pdf"))
{
    TextVerifyOptions options = new TextVerifyOptions()
    {
        // specify if all pages shoudl be verified
        AllPages = false,
        PagesSetup = new PagesSetup() { FirstPage = false, LastPage = true, OddPages = false, EvenPages = true },
        // specify text pattern
        Text = "John",
        // specify verification text pattern
        MatchType = TextMatchType.Contains,
        // specify types of QR code to verify
        SignatureImplementation = TextSignatureImplementation.Stamp,
        // specify if form fielsd should be verified
        FormTextFieldTitle = "Sample",
        FormTextFieldType = FormTextFieldType.RichText
    };
    // verify document signatures
    VerificationResult result = signature.Verify(options);
    if (result.IsValid)
    {
        Console.WriteLine("\nDocument was verified successfully!");
    }
    else
    {
        Console.WriteLine("\nDocument failed verification process.");
    }
}