Can a I, as a landlord, report my tenant paying monthly rent on time to help them with establishing their credit score or bettering their score?

Yes you can, here are a couple of links with reviews from a consumer standpoint on how that works, I have never used the services myself but I have looked into it before.

• Rock the Score
• Rent Reporters
• Rental Kharma
• RentTrack
• PayYourRent

@Kelly Martinez thanks for those resources!

@Seth Rouch   If they're looking to improve their score / build credit, two secured credit cards that report to all three bureaus would probably help the most.  The percentage of credit utilization is one of the biggest components of the score.

Thanks @Tom S. for the additional helpful insight!