Does anyone know of rules related to a director paying bank employees a referral fee for referring potential business to his company?

Ethically I don't like it, especially if it happens in the bank. It appears to be an endorsement from the bank and that could be problematic. It is especially problematic if that business deals in something you'd have to make disclosures for, RESPA, insurance, investments, etc.

When you open up this activity, you may have other businesses wanting the same advertising for for car washes, pet spas, etc. and if the business is paying the employee, the bank may be unaware of who is being "endorsed."