I've owned several H & R .22LR revolvers over the years.
They've all been 9-shot.
I've never heard of H & R having a 12-shot.
I do know that U.S. Firearms is making a 12-shot .22, and are claiming it's "the world's first 12-shot .22LR revolver" {direct quote}.
It's MSRP is close to $1,100 though!!