Here's how the thing works. Cool in its simplicity.
(I still can't take a decent photo.)

First, push the pin through about 1/2" of fabric. I find an angle works better than straight down.


Then fold the torc over the pin. The pin is kept on the torc with a ring on the back of the pin head.


Then pass the torc under the ring. The knobs on the end of the torc and its weight keep it there.