Yes what dont you understand about that. You cant cut right into the corners with a circular saw, you also need to back saw it as well with a handsaw because the circular saw wont cut the underneath of the work top as much as the top if that makes sense.
If you have a fein multi master or can borrow one, 1. use pencil to mark the worktop 2. put masking tape over pencil line (you should be able to see pencil line through masking tape, unless dark coloured worktop if so mark masking tape) 3. use the fein with the wood disc (one with flat side) 4. cut along the line cutting through formica 5. screw/clamp straight edge to waste side of worktop then use jigsaw to cut worktop, the final part needs to be finished using fein saw from top then underneath w/top 6. screw on end strip. Job done. done this today worked a treat, no damage to worktop at all. Duggie