I wouldn't include a knife in a PSK in the first place. My opinion is that you should carry it seperately. If you lose your PSK, you still got your knife and if you want to do something with your knife, you don't have to make a mess of the tin. And you can use the space that the knive takes up much better.
[color:"red"] I have a knife in EVERY one of my kits as well as a knife and a SWISS tool on my person. If you take something out of a kit/tin, just take the time to put it back into good condition. [/color]
If the knive in your tin is your back-up: I would remove it and replace it with a scalpel blade. [color:"red"] Try using a scalpel blade as a knife when you are cold, shaking, it's dark (3AM), raining, and tired. I have, I'll stick with my knives. A knife the size of a Alox Classic or Money Clip SAK can be made very sharp, and IMHO, works far better than a scalpel. "ALL of the members of a SAR team I was on switched away from scalpels after seeing them in use in the field a few times."[/color] The chanses that you lose your knife are slim, and if you do lose it, the scalpel blade is a good back-up.
[color:"red"] Or a not so good back up.....!

But what do I know, I only have more years in SAR and Survival training than you've been alive.[/color]