As far as I know, sexing russian orloffs is the same as sexing other breeds. When they are day olds, they can be sexed by venting, but after that, you'll have to wait until the combs and wattles start changing colors (the rooster's combs will grow and turn red a lot faster), they start to grow spurs (hens tend to have bumps on their legs, while roosters will grow the long spurs), or they start to get their feathers. Roosters will have sharp feathers along their back, tail, and neck, while females will have round feathers all over. Also, the feathers seem to be the best sign of a bird's gender, from my experience (I have some true araucana bantams, and they all have no tails, so I was pretty much stuck with looking at their feathers for gender.)
thank you! i watched a helpful YouTube video on sexing chicks by tail feathers but it's still hard to tell I guess since I'm new to chickens! the video said cockerels tails are "less defined" and hens have rounded tail feathers but I just can't tell lol
Once the birds are older, you'll start to see sickle feathers on the boys (sharp feathers in front of the tail). Roosters get these feathers, but hens don't.
Here's a picture showing where the sickle feathers are: http://oi39.tinypic.com/2zo9a9d.jpg