Hmmm..... Looks like a rooster. I am not sure because my hen looked like that and turned out to be well, a hen! I had an Ameraucana that at first looked like a hen as a chick, than a rooster at about 4 weeks, than at 7 weeks looked and acted like a hen! Finally at A YEAR AND A HALF OLD I figured out it was a roo due to him crowing! And he had more coloration and saddle feathers than his "girl friend".
Here is a picture of my RIR at 1 year. Yes, the hens do develop large combs too. The legs of yours look larger than a hen's legs. But I am with the others...not an expert.....good luck! Will be curious to see what you end up with.
I, too, had a RIR "hen" with a large comb, and it was slightly bigger than its two coop-mates. It began crowing tonight (August 4) at about 14 weeks.
Anyone need a beautiful RIR cockerel, raised on organic feed and garden greens? We live in a subdivision; roosters are simply too much of a noise imposition on neighbors. I need to find him a home soon. Will start by asking the local nursery which has chickens roaming the grounds.