some use 0.5 - 1 ounce per pound of soaping oils (PPO), many use 0.7 oz PPO.
exactly how much you use depends on the FO you have and how strong you want it, but I'll go with the 0.7 oz PPO
0.7 oz happens to work out to 20 grams
your recipe is 1000 grams which is a little over 2 pounds soaping oils - so I'd say about 45 grams of FO.
if you want to work in percents - 0.7 oz PPO works out to be about 4.5% so with a 1000 gram recipe (again, just count the soaping oils), you would use 45 grams of FO.