Posted 2013-May-11, 18:04
If you are playing with a partner who knows what he's doing, you do *not* have a spade fit, and 4nt is *not* RKC. Traditionally 4nt after using stayman is just a quantitative invite to slam *without* a spade fit. With a spade fit (and assuming transfers are in use, so 3♥ does not have to be used to show a hand with hearts not having spades), there are two methods that are most popular among advanced+ players to set spades as trumps and ask key cards:
Method 1: Partner bids 3♥, 3 of the other major. Since transfers are available, this is not needed with just the other major, so it's used to show a fit in the major, a game force, and interest in slam. Subsequent 4nt will be RKC. Alternately partner can bid 4 of a new suit to splinter.
Method 2 (attributed to Grant Baze): Partner bids 4♣, RKC Gerber. 3 of the other major shows *any splinter*, next step asks. 4♦ shows a fit in the major, without a splinter, quantitative slam try, not appropriate for RKC.
Be aware though, that there are a ton of (usu less experienced) players who *don't* know these things, and did actually intend 4nt as RKC. There's not much one can do about this, my policy with a pickup would be to assume method 1, if partner wanted it to be RKC after the hand, tell him he's wrong.