// Sign the app (where BinaryFile is the filename of the .hex file to sign)
try {
    
    AppSigner Signer = new AppSigner(AppSigner.Mode.DetectType);

    // Get the key file
    string KeyFile = Signer.GetKeyFile(BinaryFile);
    if (KeyFile == "") throw new Exception("Couldn't find the key file.");

    // Get the output filename
    string SignedAppFilename = Signer.FormatOutput(BinaryFile);
    if (SignedAppFilename == "") throw new Exception("Couldn't establish output filename.");

    // Sign the bugger
    int Signed = Signer.Sign(BinaryFile, KeyFile, SignedAppFilename);
    if (Signed != 0) throw new Exception(Signer.GetErrorMessage(Signed));

} catch (Exception ex) {
    // Didn't work as it should
    DisplayError(ErrorType.Error, "Could not sign application: " + ex.Message);
}