function AddSignature(doc)
{
    // if ACROSDK.sigDigitalIDPath is not spcified, ask for user input
    if(ACROSDK.sigDigitalIDPath == "UNKNOWN"){
        var cResponse = app.response({
                cQuestion: "Input your digital ID path:",
                cTitle: "Digital Signature",
                cDefault: "prueba.pfx",
        });
       
        if ( cResponse == null) {
            app.alert("No input.");
            return;
        }
        else
            SetUserDigitalIDPath(cResponse);
    }
       
    // if ACROSDK.sigUserPwd is not spcified, ask for user input
    if(ACROSDK.sigUserPwd == "UNKNOWN"){
        var cResponse = app.response({
                cQuestion: "parola1",
                cTitle: "Digital Signature",
                cDefault:  "testpassword",
        });
       
        if ( cResponse == null) {
            app.alert("No input.");
            return
        }
        else
            SetUserPassword(cResponse);
    }