I've found the skimmer effective but finicky. You do seem to need to play with it to dial it in. I had mine running for a couple of years, gatevalve wide open, and 18 or so bioballs.
I've been able to reduce my bubble size by adding all 23 bioballs. This will give you drier foam than you may have had before. You can then close the gate valve (to raise the water level for more/wetter foam) 1/4 turn every few hours (and keep your hands out of the tank, because that quickly kills foam for a bit).
This was much better.
FWIW, I'm using a SEN900 as a pump with a gate valve that is ever so slightly closed. I'm sure your pump size may come into play.
Note, the RD III is very sensitive to the height in which it is installed in relation to the water level. As a caveat, minimize backpressure by raising the skimmer.
Hope this helps