Jerry,

There's lots of threads on PSKs. FWIW here is a start (see disclaimer below):

- Personal First Aid Kit (personal health is paramount; hand sanitizer and a CPR shield may be a good idea as well).
- Emergency blanket or bag (personal shelter and doubles to treat victims of shock - garbage bags could work in a pinch and do additional duty for water collection).
- In a wilderness PSK, matches or other fire-starting methods would be carried but I am not sure how vital these would be in this situation. Do you envision someone having to bug out and live off the land for a day or two? If so then include some matches in a waterproof case, a lighter (as simple or sophisticated as you like), and the spark-lite. You may want to have several options here and give the kit user a heads up to bring their own preferred method. Some tinder quik tabs would also be a good idea.
- Water is critical so carry some water purification tablets and sturdy water bags - the Nasco Whirl-Pak® Water Bag from the PSP Plus looks promising (standard disclaimer here and elsewhere in this post). I am sure there are other options; a simple baking bag with reusable zip tie may suffice. Some tubing might be ideal to reach pooled water behind some rubble (see Doug Ritter's Mini Kit elsewhere on the ETS site).
- Whistle, bandana, maybe a strobe or signal laser or other signaling items. I am thinking loud would be more useful than bright. For versatility, make the emergency blanket or garbage bags a bright color too (that's why I like the Heatsheet so well).
- Bring along some high calorie ration bars or similar energy food. In this situation a meal can be easily overlooked or worked through and you may suddenly find yourself ravenous. Something to eat, while admittedly not critical, can keep you thinking clearly. If long term living off the land is a possibility, include a fishing kit.
- A spare small headlamp (DRs eq headlamp comes to mind - don't forget extra batteries), a good plier tool, and mini sharpener. Not sure what other "tools" might be useful.
- Spare goggles and dust masks or respirators (there may be access to something a lot better but this is what I know - see disclaimer below), wipes, tp, insect repellant if bugs will be an issue, sunscreen, and sunglasses.
- Some wire, paracord, duct tape, sewing kit, safety pins, fresnel lens, aluminum foil, paper and pencil, and rubber bands.
- Navigation items like a compass are also normal for a wilderness kit but thinking these would be less critical in this situation.
- A prybar and jack-hammer would be nice but won't exactly fit in a small kit.

I mention my disclaimer again that I am not a professional, just thinking along PSK lines here. Others will have better input I am sure. Any items already being carried or deemed unneccessary could easily be dropped from the kit and replaced with other more neccessary gear. You could also start with a PSP and add some of the suggested items that are missing like the FAK, emergency blanket, water tabs, water bag, tubing, bandana, rations, headlamp, batteries, plier tool, mini sharpener, spare goggles and dust masks. Hope this helps.