You are best doing it in the syringe (you can hold the pig firmly, you won't hurt them!) They may not eat food that is doused with antibiotics, and it is easier to get a syringe of meds in quickly than to get them to eat a piece of food they don't want.
My technique for giving meds is to put the pig in my lap facing away from me, stand them up on their back feet with their stomach supported by my hand and their back pressed up against my stomach, and then to use my other hand to stick the syringe in the side of the mouth (the area between the front teeth and molars where there are no teeth blocking the way) and then to just get it over with as fast as possible. Sundae was on chronic medication for years, so I got really good at this and it does work, but it takes some practice!