Shelterluv isn't compatible with any particular signature pad since it is a web-based application, thus, any signature pad that works in a web browser (preferably Chrome) should work with Shelterluv as well.
One example of a signature pad that has been reported to work well by users is the XP-Pen G430S OSU Tablet Ultrathin Graphic Tablet (please note that your computer must be compatible and recognize this as a mouse device). Signature pads have also already been discussed at some length by other shelters in our Customer Success Facebook Community and you may find some good suggestions there: https://www.facebook.com/groups/shelterluv. Instead of submitting a new post, you should search "signature" in the box on the left to pull up those discussions.
For any transactions where you are using the text to checkout feature (if you use the integrated credit card processor, Stax) then the transaction is sent directly to the adopter's phone and they will sign with their finger right on their own screen. We do recommend this method for digital and contact-free checkout. See this article here for additional information on Setting up credit card processing through Shelterluv.