Huh, I happened to just see a thread about this the other day. Di recommends putting 4 coins on each of the corners of the foil (that is, under it), then setting something across the top. Well, so the foil can be flexed just a little bit in the opposite direction.
In other news, I'm actually buying cards for this. I just won a foil jitte today :P
And on topic...Yeah, got nothing, sorry.

