He might not pick on her unless he is an aggressive rooster, try keeping her in a cage in the coop for a few days so they can see and recognize each other. He might even take to making him one of his "girls"
i tried to throw in my silkie girl at night with my OEGB and the roo kept staring at her and would get all scared... LOL... then he would forget about her, turn around, and start a commotion all over again... all of my roo's were making the INTRUDER noise, so i had to take her out... that was hilarious and upsetting at once... he sees her out when they free range, but doesn't do a dance or anything... i dunno what he thinks she is... she doesn't make noise, she's super quiet all the time... weird...
but... i have seen silkies in with other game cocks and even seen silkie old english mutts...