The tricky thing with referrals is the rewards need to be appealing/enticing enough to motivate people to share. Also your messaging around it needs to be spot on. It can be really tricky to convince people to do this. Honestly, I'm my experience, appealing in a direct, conversational tone and asking readers to share and recommend your content to a friend or family member who might find it useful/entertaining is more effective than setting up a rewards based referral program.
Happy to take a look at your offer though and offer some advice!