The inquiry is, if you should - and how you should - reward a referral source that generates a lead.
My philosophy on this subject is based on the law of reciprocity. I do not expect, nor do I give a 'reward' for referrals, but I have always believed in helping others to grow their businesses by offering appropriate referrals to them whenever possible. Even when meeting with a prospect and discover that their real need is for a service outside of my areas of expertise, I will refer them to someone who has the specific expertise they need.
I do this in a spirit of good will and expect nothing in return except their continued success. But, as a result, the gesture usually returns to me in the way of lead generating referrals from them!
This law of reciprocity garners trust and appreciation among fellow professionals, working together for the greater good of the business community.
Hope these thougths are helpful.