They fit on top, it's a bit fiddly but everyone should be able to do this with a calm hand and a toothpick.
I am in touch with the guy and I think there will maybe another design available.
But I have no clue how complicated it will get when having several different designs.
I quite like the gold/red on the black HHKB but some people think it's to harsh and want something less noticable
Hang on guys!