Pict, the point is that your knife (rigged with the stuff you couldn't live without) IS your PSK. Who says it has to look like a box! My PSK is either in a waterproof neck pouch, or (believe it or not) in an old leather "secret zipper compartment" money belt. But, as Presumed Lost says, it consists of the bare minimum I think I'd need to keep alive until help reached me, considering the geography I'll be in.

In the past, though I carry many less critical comfort items (usually in a small fanny pack)it has taken discipline not to raid the PSK. E.g., when my pocket lighter failed, I'd use the bic in the PSK to light my pipe or cigar. I've gotten better about that. The PSK is last ditch survival, nothing less.