The Protekt is a Dyna-Gro product, it was just another example that for every Advance Nutrients product, there is a product for less $$$ that is either better or just as good.
Not only does Rhino Skin cost almost twice as much per liter as Protekt...but you have to use 4 TIMES as much of it. Protekt is 2ml per gallon and Rhino Skin is 8ml per gallon. I use Dyna-Gro Protekt, it's awesome stuff.
When I was using AN I was getting about 400-450 grams per meter. AN may increase your yield from what you are at now (after you dial in the products which could take a grow or two) but it will cost you LITERALLY at least 2 or 3 times what you are spending right now and you will be mad at yourself in the future. Like I said before, I still get about the same yield with better products, spend waaay less, and have healthier better tasting pot and food.
But since you asked what you should use, I'll answer your question.
But I'm going to leave a suitable alternative for you next to them as well that would be cheaper and probably better..This is what I used that I wasn't ENTIRELY unhappy with.
Iguana juice - Grow and Bloom (GO Grow and Bloom or Bio Canna Vega and Flores)
Nirvana (Seems like a compost tea will accomplish most of what this does. Also, GO Bio Bud or Bio Canna Bio Boost)
Organic B (Thrive Alive)
SensiZym (Hygrozyme_
VooDoo Juice (GO Bio Root)
F1 and H1 (GO Diamond Black)
Bud Ignitor (A lot of nute companies have a product that speeds up flowering a little. This product actually works, but is expensive. But the gallon if you decide to use it.)