Help...round flat panel

I’m using a round loom and instead of gathering the top of my hat like always, I want to cap it off with a round flat panel. I don’t use needles and was hoping to use my round loom. Can you help me?

The vast majority of knitters here are hand knitters with two needles. There are a few loom knitters, but you’ll need to be patient to get answers if they know them. Or try Google.