Model release form

Hello:

I am a stock contributor and I want to setup my Ipad to have models sign a relase form electronically.  I installed Adobe sign, but it does not like Adobe's model and property release .pdf forns I downloaded from Adobe,  AdobeSign  gives an error message that the file is not compatible.  If you have an Adobe model release form that works with AdiobeSign, I would really apreciate it if you could point me to it or share it.  Searching for a solution I see that some photographers use a Photoshop file for that purpose and not Adobe sign.  I could use that as I have PS on my pad.  If you have such file, I would also greatly appreciate it if you could share it,  Or suggestions for an alternative and simple solution (electronic!).