Don't try to slide it on. I think you will scratch the snot out of your receiver. I loosend the screws enough, pried just a little with a big flat screwdriver. It didn't open it up all the way but enough to place on the dovetail, pushed hard and it popped into place. Yes, a bit scary but it worked. Because the receiver is crowned it spreads the mount as you press on it.
I read the darn directions hoping it would give some guidance but as you probably know it doesn't say much. I think it got lost in the Chinese translation...
Andy Wong aka larspawn