Our daughter did not have stomach issues, so I'm not sure this will be the best advice for you... but I wanted to share what our pediatrician said (and we love her--she's a GREAT doctor). At about 9 months, a baby's stomach is not so sensitive so you can start using "less fine" formula. My husband did some research and found on Consumers Reports that Parents Choice (sold at Wal-Mart) is a great brand--comparable in ingredients and definitely far less expensive than name brands. It's inexpensive enough that you can buy a container and see how well your baby tolerates it. If it doesn't go so well, you don't feel like you spent a fortune just to throw it out.
As far as adding rice to the bottle... I think that that's the difference with the regular formula and AR. I, personally, didn't like AR because I spilled formula more often when it was the "thicker" one. I added rice cereal on my own, after adding the regular ("finer") formula. Again, my baby had no tolerance issues--it was not to combat reflux; it was because she was a big eater and I needed to make it a little more substantial for her. Parents Choice is worth a shot. Or try soy instead. A few or my friends have done that too, and it worked for them.