That is what I used. The holes on the hand rails will be square to the rails. It's the cabin top holes that will be at an angle.
I think the WEST website recommends using an old fashioned can opener to scrape out a "V" groove and then apply the epoxy. This is the kind of can opener that has a "V" shape on one end that you used to use to open beer cans before they invented pop tops. The other end was rounded to open beer bottles before they invented twist off caps. So pretty much any rigid piece of metal with a "V" shape will do the trick. Don't use epoxy if the repair will be in the sun, UV degrades it. You will need to add gelcoat over the epoxy or paint it to protect it. If it is entirely under the toerail you should be OK.
Your objective is to create clean edges so that the replacement epoxy/ or/ gel coat has fresh material to adhere to. I've used a dermal tool to open up the crack. Clean the gouge with acetone soaked rag to remove all dirt and oils. Then apply the new epoxy/gel coat to fill the crack. It may take more than one application. You may also want to add a filler if the V-groove is too deep or wide. Be sure to carefully tape off the area you do not want epoxy. It is much easier to pull tape than sand slop over epoxy.