I have an RM Low Rider IWB for my Glock 19 and like it so much, I have ordered one for my PPK/S too. It is incredibly well thought out and designed and very comfortable...you won't believe you're wearing a piece of kydex! It FITS and it works as advertised. It's a bargain too; like $55 including shipping and about a 4 week wait. Easily the best dollar for dollar holster I own and I own Rosens, Kramers and Alessi holsters too.
I am not affiliated with RM holsters, but this guy (Rocketman)knows his business...his web site is weak, but his gear is rock solid. Google 'em and check it out for yourself. Rocketman holsters rock.