I can't read those labels, but if the pig is getting pellets with stabilized vitamin C as well as veggies with C, I wouldn't give more than 25 mg per day, and for no longer than a week.
The bottle should say o how many milligrams of vitamin C are in 1 ml of the solution, so you should be able to figure out how much of a ml to give to get 25 mg.
The only info I can find says there are 250 mg. of vitamin C in 5 ml. of solution. That means there are 50 mg. in 1 ml. So if you want to give 25 mg., give .5 ml.