Yes, you should be able to do just as you did. However, kbin.social's federation isn't working 100% right now due to the influx of people and cloudflare stuff. If you look over on fedia.io you can see what it's supposed to be like when things are actually working properly.
Basically: just some technical difficulties due to reddit hug of death. once things are running smoothly you'll be able to interact between the two sites normally.