I guess one could measure the powder, per a 0.2% concentration of the future spray mix, but place it initially in a small amount of warm water for a few hours, perhaps with blackstrap molasses to work on. Blackstrap is also a traditional micronutrient source.
To activate baker's yeast, get a cup of warm water (110 F) and sprinkle yeast on top. Following Har's recommendation, probably would be good to add blackstrap molasses (1 teaspoon) at this time. Yeast feeds on sugar. Wait 15 minutes, and should be ready. Then mix in the kelp, wetting agent, and water to make a gallon of spray.
Seems it would work well with pawpaw. I sprayed avocado flowers recently, going to hit them again in a week or so. My avocado tree (oro negro) flowered for first time last year, held fruit for a while, then dropped all fruit. Hoping for better results this year. Tree is 100% in bloom.