How to pop out SN process in Salesforce into a new window?

This can be changed in your button settings in Salesforce settings by going to your Object-->Button & Links--->click the SignNow Button ----->Click "edit" and change the display "Behavior " to either pop out a new window or keep it in the same frame. Page 10 in the guide will show you how this is done.

Watch the SignNow API in action: