Since keel strips are usually just 'wear away' additions, you have lots of choices, IMO.
You could use just gelcoat (layers), sanded smooth, without tape.
For resin, polyester resin will work OK for a keel strip - I'd use epoxy for anything 'structural'. Polyester is cheaper.
I'm assuming you don't have a gallon jug of epoxy in your shop.
You can also soak tape with gelcoat (or wet the tape with clear resin and then lay it into gelcoat and top it with gelcoat to add the colour).
Using polyester resin, you could use mat strip instead of cloth tape. Mat is easier to shape to curves (and is thicker) but tape works fine as well. With epoxy, tape only - epoxy won't dissolve the binders in mat.
For the 'where to get it?' question, where are you located? (You can add your location to your profile.)
I'm not a big fan of keel strips - I usually prefer to just repair the gelcoat.
You could just stick on a length of KeelEzy if you want a keel strip. It is popular but I think it's a bit 'sticky' when the kayak gets hung up on a rock. Just IMO.
