Photos and/or links are the best like Wayfinder says, but this is what you get with a !/2" radius bit. I use 1/4" on front and backs of headstocks. These bits have a bearing on them that only allows them to cut a specified amount. You can band saw or use a belt sander with an aggressive cut belt (like 50 or 60 grit) to cut taper on back of neck up to head. That bearing is a follower so you have to have a smooth edge for it to ride on. If it hits a bump,it duplicates a bump on the neck. P.S. This makes sense to me, but the inside if my head is deranged. If you are not clear ask again.
What i've seen of them Doggly,i think you will need a 1/2" router,and as there's no guide bearing,a router table or jig and take a pass from each side,pretty simple,but i'd think easier to do on thicker stock prior to ripping to fretboard thickness