Scottish? I thought it was pan-British Isles, as i was exposed to it in the south of England. Like a reversed American "peace" or "victory" V, with the back of the hand forward. The historical origin of this was English archers taunting their French foes (who would apparently cut off these fingers on captives to make them useless as archers). At least, that's how i've heard the story.

If you happen to be in England (or Scotland, i guess) and you want to answer two to "How many more exams do you have?" or "You have how many lovers?", remember to put your palm forward, not the back of your hand. Well, for the latter, either might be appropriate (your call).