Yeast energizer

I just picked up a yeast energizer powder from my local supplier as I have a dark ale with some sluggish yeast .. Problem is I don't know how to add it properly.. Do I mix it with water and pitch it? Do I sprinkle it? Could use some wisdom here... I have the same questions with regards to my gelatin finings .. Can't find anything online to help..

Energizer or nutrient should be added in the last 10 or 15 minutes of the boil. When I use Gelatin I mix a half tbl spoon with a cup of water and add it to the keg right after racking. If you bottle, mix it in your batch with your sugar.

I was given the advice to add this energizer to my mead after my 1st week in the primary .. Reason being that my OG was 1.034 and after a week 1.020 ... Which my supplier said was sluggish... So I did what my supplier (and long time brewer) suggested and added the energizer ... Well once I added it I went from having no Krausen left at all to about 2 inches or more and an impressive amount of activity .. It was pretty cool .. But could this have damaged my beer? The idea was presented to me as it will "take the fermentation the rest of the way" I plan to leave it alone for two more days and then transfer to a secondary for 2 or 3 weeks