Gouda is my all time favorite , I do them regularly.
For 4 gallons (16l) , I use 1/4 tsp meso and FD.
I use rennet tablets , 1/2 tablet works fine for 4 gallons.
After cutting and washing curds , I put curds in mold and put it back in the whey and press under whey.
Make sure to add the calcium chloride and vinegar to the brine , the vinegar really sets up the rind nicely so the cheese will hold its shape later , and dries it nicely for coating (I coat mine with PVA).
That works for me.