Funky,
If you get some good quality food (I use Optimal BG) the perch will soon be there to eat it. I hand throw to the same spot in the pond and not every day like I should but when I get a chance or when the weather allows. The YP like to stay hidden I the deeper water and you won't see them very well as they make stealth runs then dart up to grab and then immediately back down. The bigger YP will stay on the bottom and just eat the leftovers as they sink.

I only feed when water warms up a bit in spring through late fall when water is getting cold again. If you truly have YP only in your pond then you might not to get to see too much surface action like you would with other fish. But they are eating it and will get nice and fat.

I have no idea how to feed in winter as we want to skate on our pond so keep it as frozen as possible.

The forage for my YP in winter is scads of young GSH, probably they eat a fair amount of the young of the year of their own babies (YP) and may eat snails, crayfish, and perhaps a few baby RES?