I also have LPS. To feed you need to turn of pumps otherwise the food just flies around. Also lights have to be off for an hour or so so that they have their tentacles out for feeding.
Whatever you feed should be choped up very fine. Yes they can eat bigger pieces but from what I have read they really don't digest big pieces well. You can get a lot of things at local fish stores to use as food. Shrimp, squid, silversides etc.
After it is chopped up, mix it with a small amount of water. Get a dropper at a drug store and use it similar to a turkey baster. I found the turkey baster to big and messy which is why I use a dropper. Suck up some food into the dropper and then feed some to each coral. Give them some time to pull in the food before you turn pumps back on. You may want to use a net after you turn it back on to catch food that is now flying around otherwise you can end up with algae problems from all the extra nutrients flying around.
You will have to do it a few times and then you will see how each one actually eats and how much. Let me know what you have and if I have it I will tell you how it feeds.