NickH

The trouble with skimming out with rapid set is that if you end up with "bumps", the stuff will be rock hard before you realise what you've done. If your walls aren't too bad then I think your better to tile straight on with rapid set building up locally as needed and taking your time to get it flat as you go. I've done it that way many times with no probs and if you do use rapid you will be able to grout same day.