I used a realtor to find a new tenant for my rental. He retained a service fee from first month‘s rent so I don‘t have an invoice. Do I report his commission on his 1099?

[Critter-3]

First you should have gotten some kind of receipt from him, they may send you something in January.  However as a landlord, reporting the rental on a Sch E, you are NOT required to issue them a 1099.  You can either enter the total gross rent less a deduction/expense for his fee  OR   the net rent received.