I think it will come down to the individual fish personality. If the Betta is used to being alone, they might not like sharing the space. But for a Betta who always has tankmates without incident...I doubt the Ram will start causing problems.
Female betta - Definately should be fine
Male Betta - I would think it would be fine, i was told just try to stay away from anything with a flashy tail (fancy guppies) that the betta could confuse for another male. But then again, it depends on the certain male's personality.
Rams are really on nippy towards each other, OR when another similar-sized fish comes into their territiroy IME. I would say no for a 29G. I tried Rams and Bettas once...The Rams terrorized the male Betta for 20 minutes when I finally said enough is enough in my old tank years ago
It was a 55G w/ 6 Rams, but it was overstocked (College Tank that I had in the hallway for everyone - Didn't work out well)