Rithmic connection

Hi!
I didn't take any modification yet in "Rithmic sample application" and I would like to connect with it but I don't know what certificate file should I use!? I just have a username and password for my account and nowadays I use it with Ninjatrader well. I have found a certificate (*.pk12) file in NT's folder but then I got a "bad input" error message which is understandable :)
I should request a valid certificate file from my futures broker or what file do I have to use there?
Regards,
Jose