Actually, since I have been in here is 2-3 Tablespoons per gallon!! If you put it in a spray bottle, just a quick squirt on your hydrometer etc., waitabout 60 seconds and good to go.
Same ratio for your carboys etc. T rinse or not after? I think we still argue about that.
I dont have running water, so I do things a bit different.
I fill up my 3 gallon BB carboy half way with warm water, add 5 or 6 tablespoons Kmeta. Put a bung on it and shake the hell out of it for about 5 miutes, drain quick rinse and drain.
I think I got the 5 minute contact info in here, but just not sure.
Sanitizing as w know is crucial.
But when added to your wine in the primary is important as well and in fact, IS a form of sanitizing. 1/4 teaspoon, not TBLS, in 5 gallons should be around 50ppm. Thats what you want.
I am sure others will chime in, keep an eye on this thread.