For rent by owner, applicant brings realtor...who pays realtor?

[Alyssa K.]

First investment property (Texas), currently accepting applications. We aren’t using a realtor, I have a marketing background and have been able to drum up enough interest without one. If an applicant is using a realtor, will the realtor expect to be paid by us? For the particular applicant that raised this question in my mind, her friend found the listing, I spoke with the friend, then I reached out to the prospective applicant, I coordinated a time to meet and show the property to her and her fiancée; then she lets me know she is working with a realtor. We are using BP paperwork for the application and lease. After doing all the “work” I don’t want the realtor to expect a commission for just coming to the showing with them, but want to make sure I communicate this in the right way.