We feed our 2 geldings in a low cattle trough. What I do is before I unlatch the gate, I make the horses back (they will do it on voice command.) I don't even unhook the gate until they have both backed up. Then I carry the feed bucket in my left hand and I use my right hand as a buffer between me and the horses. When we first started feeding them I carried a 2" stick to help keep more distance. Then I walk to the feeder and the horses must be on one side of the feeder with me on the other side. I don't pour one single grain of feed into the trough untill the horses have calmed down and If they try to come on my side of the feeder they get chased off.
It took them about a week or so before they realized that I own one side of the feed trough and they get the other. They both will wait for the feed to get poured and then I thump the bucket a couple times which they aren't all that fond of but they know its comming so they don't just dive into the feed. After I thump the buket then they go about eating.
Anyways, right or wrong this is what has worked for us. Hopefully you can adapt it to work for you. Good Luck!