Portrait is fairly flat, which is typical. Is there any trace of solder from a suspension mount on either side or the edge? Spink ticket and price suggests it will probably be in the Circular, but when? I'd have to plough through them to find out.
I can't see any case for it being a touchpiece, as these were typically angels - the combination of saint and king provided the cure and/or protection . The milled Charles II touchpieces were produced later than this coin
FWIW, this is my 3rd issue shilling. Again, flat in parts, though the portrait is above average.