I used the heels on a custom I gave as a gift. I have several pairs of them, that I either got in an auction lot or from the doll stand at the flea market. The stamp on the bottom says "H.K."
I think the flats were from the same place as the heels. At least, they're in the same baggie with some boots that look like they belong to Charlie's Angels or Maddie Mod. They say, "Japan" on the bottom.