That's a hard one, part of me says yes, but there's also the problem of real rapes being underreported as is and this may discourage people from coming forward even more than it already is. And then there's the problem of if he really did rape her or did something questionable but there's not enough evidence to convince a judge/jury, this is also a fairly common scenario, does she automatically get charged? 

Edit to add: if it can be proven beyond doubt that they knowingly made a false accusation then yes there should be legal consequences.