Perhaps a version without the payment aspect but with rewards would have been received better. Say a potential referrer would sign up and get three reference tokens (which expire) periodically. Then they can use one to support a person they know for a position. If the employee lasts for two months, they get two tokens and some monetary reward.

Honestly, the barrier of having to sign up to act as a reference for someone might be too much on its own. But, if they manage to get people with good professional networks participating it might be valuable.