I finally put my nasty RIR on time out. She's in the cage that we used to transport the hens originally, set right beside the coop. This is a new flock, all new to each other so I knew that the pecking order would have to be established but she is NASTY. Her and our BR are fine and the BR actually fights back a bit when the RIR picks on the other girls but our poor Columbian Rock and Silkie are being mercilessly bullied by her. ARGH!
I hope that your RIR will settle down in time. I have only 2 hens. My old one is a Warren aged about 3 years. Her companion died a few weeks ago so I got a new 'black star' aged 17 weeks. I have been leaving them with fence between them so that they can see each other but not peck. I swap them around so that they go on each other's territory. At first the older one was so furious that she yelled at the top of her voice whenever she saw the other, but I think that things are improving. You would think that the old hen would be pleased to have a companion, but I am not so sure. I think that separation is the first step but perhaps a beak bit may help if the violence persists.