I just posted a pic earlier today of a RIR that I bought as a pullet, but then it started looking so much like a roo that I was totally convinced it was, but now looks just like a hen again.
I posted her photo here just to be sure it was a female. I swear she had me thinking she was going to crow up until a week or two ago. Oh, and I only have one RIR, so I didn't just get some mixed up.
Some breeds are just so obvious, but evidently the RIR's are a little harder to tell.
Didn't help you any did I? Well, I hope it turns out to be just what you need. Good luck!