Digging through asphalt for fence posts

You may not need a hammer drill. If I were renting a tool I would go with a small jackhammer with a chisel bit. I rented one to tear out old floor and wall tile in an old bathroom. It has the thick mortar and chicken wire behind it. Did the whole room in a couple of hours. Rented it at Home Depot. What are you planning on using to secure the posts? Going with concrete or trying to use asphalt again? I would get some post hole shovels and go at least a foot deep from the surface and use concrete and maybe top it with asphalt if you can. But that’s just for looks.