We launched a pretty big new integration at Rewardful yesterday. We now work with Paddle, so if you're building a SAAS with Paddle as your payments provider you can set up an affiliate program on Rewardful.
If you want to learn more you can visit http://rewardful.com/paddle
Like your product and how it helps SaaS companies! I recently helped a similar project get paying users in 90 days. Can help you with sales and market positioning, just DM me on Twitter :)