Hello and welcome
The "norm" is 1lb of feed per months of age per day - so a 2 month old pig would get 2lb of feed a day, split into at least two feeds. This rises to a maximum of 6lb per day BUT with these traditional breeds, some folk cap at 5lb.
Also if you are feeding veg or fruit, cut back the pig feed at a ratio of 4:1, so if you feed 4lb of fruit / veg, reduce the pig feed by 1lb.
Also chek their condition by feeling for the spine - if you can feel it easily with little or no pressure, the pig is thin; if you can feel it with firm pressure, the pig is fine; if you can't feel it at all, the pig is too fat.
We've always worked on this but there are others on here with more extensive experience than I