Apocalypse by Harry Lorayne Volume 8, Number 1 January 1985 Page 1018 et seq.
Personal Comment: This is a tricky little trick. It can work in quite a few different settings and fail in a lot of others. In fact you should not riffle shuffle the deck near the tabled cards. The effect is not new, but I guess this could fit in a gambling demonstration. I kinda like it. Kinda!