What is Opener’s rebid?

Julian Pottage's Answer

It is a close decision between 2H and 3H. The fact that you have only 12 HCP suggests 2H whereas the Losing Trick Count suggests 3H. Personally I think it tends to be easier to make the slight underbid, knowing you can then co-operate fully if partner makes any sort of game try or slam try. If you are asking the question because whoever held the hand made a 3S splinter, I would have to say that is a clear overbid. While it is good describe the shape of the hand, the strength of the hand would need to be good enough to be committing the partnership to game, which this hand is not.