i pick a kit up from wenonah for my prism. it did not come with one, but has the metal inserts in the interior ribs.
i know that is where they are riveted on, but my question is do i just make the entry hole with the drill bit and just push the pop rivet into the foam.
really no need to go very deep, right?
looks pretty simple.

the project went as planned, no issues. one tip is to start the drilling with a very small bit, then finish with the 3/16th bit.
good project on a cool iowa day.

Can you provide picture please? Usually I see that the head of the rivet is on the outside of the hull where there is more surface area contacting the head. Then the expanding part of the rivet sometimes has a small washer against the angle to give the aluminum more surface area for strength and less stress against the hole.

Ok I see, adjustable footbrace. The rivet just goes to rib not to outside of hull. No holes, no rivet head outside. This will work but you should check and make sure it is nice and secure before each trip, the expanding head on one layer of kevlar is the weak point.

wenonah molds in a metal plate on each rib where the pop rivet holds very securely.
it's solid. the canoe never came with one, but in their production, they make sure it was set up for one.

I pop riveted an adjustable footbrace into my C1W in 1983, no ribs (actually, center rib, but none on the sides). It's seen a lot of use, and has held up without an issues--no cracks, original rivets are still holding. You should be fine.