Meanwhile, the Richardson S/M is almost too big for me. Rather noticeable after I get a haircut... but it's what I use and all I've ever used.
Hat too big? Put distilled water in a clean spray bottle and thoroughly wet (soak) the headband. ‘Ball’ some clean wash cloths to create a loose ‘form’ and place it inside the cap, just to hold the crown in place. Don’t stretch the wet hat. Let it dry naturally, and thoroughly. Don’t be in a hurry. Let it dry thoroughly. It will shrink, usually around a half size.
Don’t use tap water, or even bottled drinking water. Distilled water.
Once shrunk, they tend to stay shrunk, unless they get wet, again, and stretched.