You need to be able to adjust the air flow. Just restricting it would abuse the pump's diaphragms. Rather than restrict it. I would divert some of the air. You can get a valve with one input and two (or more) adjustable outputs. Use the middle output (between the input and the other output) for the skimmer.
The other output could power an air stone or something. How much you open this valve will control what's available to the skimmer. I found that an air stone will quiet the exiting air, even if it's not in water.
An adjustable pump is nice, but you still need to regulating as above, too.