have you considered this one craigy?http://www.heinnie.com/Knives/-UK-Legal-Carry-Knives/Sheffield-Knives/Sheffield-Small-Penknife/p-92-641-660-1610/
The subcom 42 is a bit big for keychain use I'd say.Michael Morris does a small version of his famed Friction Folder. Also has a useful bottle openner on it.There's a photo at the bottom of this page on his website http://www.michaelmorrisknives.com/current.php