I couldn't find anything on it either and I couldn't find a skimmer small enough for the space I had at this new pond. So, we are building one and we'll see if it works.
The pond is underground walled with concrete blocks. There is a lower area for the water to fall over, a sump that is longer than it is wide that the water will run through and then drop into a hole where some kind of filter will precede the pump. Haven't got the filter part figured out but it could just be 2 screens with something between them. This will be opposite the bog and the waterfall hopefully pushing the water into the skimmer. It's a small pond, surrounded by the walls of the house and a concrete patio so we had little choice in the size and placement. There just wasn't enough room for even the smallest skimmer I could find.
Here's where we are now. We stopped working on it because we need to finish the remodel of the guest room inside so Mimi and I can move in there and get the transmission of our RV repaired. We should be starting up again next week.
The main part of the pond will have liner and we will take the liner into the skimmer as best we can. We also have some
Pond Shield epoxy that we're going to use for the pump well and most of the skimmer. We're also using it in the bog above the level of the liner. The bog will be 2 - 3' above the pond.