Im new to this, but from what I have found out by research and others telling me information on sexing, I would say that it is a pullet because the comb has no red or pink color. I know different breeds may take longer to show but I have 8 RIR chicks and the roos started showing pinkish/red waddles and combs at 4 weeks.
Im pretty new to this as well. Its nice to know im not the only one. And yeah thats what im thinking too but im afraid it is a roo because i just dont want to have to get rid of him.