Tough to find organically sourced K in a soluble form.....liquid seaweed/kelp is about the only source I am aware of. Seaweed extract is about 1-0-4.

Bonemeal, kelp and woodash offer potassium. If you compost then add them and mix in.

Is your need determined by symptoms of deficiency or a soil analysis?

Sorry, delete the bonemeal. What was I thinking.

A soil test will identify if deficient or blocked by an excess of another nutrient.

Check out the link.

Here is a link that might be useful: Organic Fertility and Nutrients

yea i have been looking into getting a ph meter so i can see if its locked up or if i really do need more K. thanks for the advise. do you use a ph tester? if so what kind? i want to order one but I'm not sure what to get?

How do you know you need more Potash?
Is this simply a supposition based on the theoretical nutrients in that liquid feed?
What soil is this tomato growing in?
Could that soil have sufficient levels of K for the plant?
Keep in mind that excess levels of K can interfere with a plants ability to uptake and properly utilize Nitrogen.

I'm putting my ashes from my fireplace both into my garden and my compost pile plus my worm bin this winter.

why? It raises pH. Does your soil need that?

I'd be very cautious about putting wood ashes into a worm bin - they are extremely alkaline and also very caustic. Adding much will make the pH inhospitable for the worms and the chemicals could kill 'em. Most vermicomposting sites recommend against it but even those that OK it suggest only a pinch occasionally.