Hi flashman.

If you get hold of a British Army Ration pack you'll find inside lots of goodies including 10 Lifeboat matches and a Striker pad. The ten lifeboat matches and striker pad will fit into your PSK.
Alternatively you could also carry an equal amount of strike anywhere matches and a strip of ordinary sandpaper.
Stike the strike anywhere match whilst holding it against the lifeboat match, this will ignite the lifeboat match easily. I store both matches in some waxed cardboard which alternately has a row of lifeboat matches heads at one end of the cardboard and the strike anywhere matches at the other end. The waxed cardboard keeps both types of matches waterproof and the waxed cardboard will also act as a useful tinder.