This is a guess, how about doing something like this:
Make sure there's an anchor strip along the external top and bottom edges (plus maybe have any plane[s] that may tie to the edge plating extend out to the edge[s]) and having a callout on the fab drawing that points to the relevant edge(s) that states something like:
"Edge plate indicated area using nn oz. Copper. Deburr and break sharp edges."
With the addition to the note of something along the following if there is/are any plane(s) that tie to it:
"XXX Plane on layer(s) N (and N) must tie to the edge plated area(s)."
I have an email in to a friend that works at a fab, to see what they might want, but it would be tomorrow sometime before I would get an answer.
Does it have to be a flat edge? I've seen some people having success with putting large vias on the edge and then milling through them. You'll get a half-circle/arc that you can solder to connect the board in a stack.
I was thinking that using a plated slot with breakaways (mouse bites) might accomplish what you want to do.
What you are looking for is called "Castellation", here is an info link from the web. I suggest working with your Board Fab house to define it properly on your design database.
I got a response from my source at a fab.
She said what I stated is pretty good, with this additional commentary:
What I asked (pretty much what I posted above):
[Subject] Do you have any examples on how to?
Call out edge plating on a PCB? And what is required of a designer to set up for edge plating?
Could it be as simple as making sure there's an anchor strip along the external top and bottom edges and having a callout on the fab drawing pointing to the relevant edge(s) that states something like :
"Edge plate indicated area using nn Oz. Copper. Deburr and break sharp edges."
Pretty much. You usually need to indicate the “contact points” where the plating is not located. Min 2 places but generally one min on each side (4) Your artwork needs to show metal to the board edge and indicate edge plating on the print. Generally plating thickness is not called out because it is the same .001 copper that is in the hole walls.
I didn't even think about the use of vias or other drilled holes along the edge (I assumed you wanted a flat edge).
One method I used in the past was to create a long slot along the edge of the board to be plated. That makes it crystal clear that the edge is to be plated. They will fab it like a plated-through hole, then route into the slot when finishing the mfg.