First of all let me say that I have no set ingredient amount but can offer this. Per 16 Ounce of water and a little honey in the mix (so the bees will lick it off each other and get it internally as well,) I user one drop of each oil(NOT one dropper) if using Young Living Essential Oils. I am not a reseller of these oils, it is just my experience that these are truly therapeutic grade oils that have not been cut with anything synthetic or diluted, so they are highly concentrated. Then as far as the lecithin is concerned, I start with a teaspoon, blend it all up and then see if the oil is thoroughly mixed in. If you see oil sitting on top of the mixture, add more. I am using Whole Foods brand soy lecithin, which will not hurt the bees at all. I never drench bees. I lightly spray them during the late spring, all through the summer, and fall before the weather turns, I spray them every couple of weeks. WHY? Because this is not a dramatic wipe out every parasite and hope some of the bees survive trip like the heavy chemical usage is. IT IS more labor intensive then using chemical products. What I end up getting is strong bees that can fight off anything with little to none parasites. So, I put the effort forth so they will thrive. When your weather is cool...consistently below 60 degrees...I will not wet bees with anything!
Hope this helps.