I have been trying to find this, but I have no idea where it is. I imagine I have to find the Snatcher, but is there anyplace I can get to him besides repeating acts over?

If you pay attention to the ground, you might notice some plants growing in a circle. Enter the circle and the Snatcher will appear and have you sign another contract.

I recommend doing so as soon as you can, even if you're in the middle of an Act. Once you've signed the contract, Snatcher will disappear and you are free to resume whatever you were doing, so it's not like you'll lose any progress.