Pick a starting point and just go for it. Be it a feeding chart, or what I've done is start at 25% of recommended dose in bottle (wasn't GenHydro). Then you watch the plants see if it's too much. If so dial it back, other wise increase it a bit more the next feeding, until you tech your max level. If they are under feed, up the percentage more. The key here is to watch how they react, thats probably the best thing you can do imo. Otherwise if you follow feeding charts and something goes wrong, you won't recognize what's going on.
It's impossible to give you a very specific ml recepie optimal for your plants in your garden without lookin at it in depth. But the charts are a good starting point if you have no other and absolutely need one.