Getting Paid For Finding A Buyer For A Realtor

[Khaliq King]

Greetings,

I work as a wholesaler and I found a buyer for a listing on the MLS. What document/ Addendum would I need to protect my fee.

The listing agent is being very cooperative and has asked me to send her an addendum to the "as is" contract so my fee can be included. 

Any ideas where I can find this?

Appreciate the help

Khaliq