If he is going to accept it at all, it will cost around 6K. Some players will not take it no matter how much you spend, though.
Interesting sidenote, I was just recruiting a 5 star Intl and was losing the battle so I wanted to get off his list. I pulled his offer and informed him of RS. I could not get off his list though, since he was 100% COOL WITH THE RS!
Unbelievable, but it seems Intl recruits are fair game for a RS no matter what their star rating is.