How to apply silicone to an edge (tidily)
There is a little gap between the coating of the top and the coating
of the side

First is to make sure the &quot;coating&quot; is securely glued down.
I use painter tape to mask off any area that i do not want caulk on, put the tape right up the the edge of the gap on both sides.
Apply the caulk with a caulk gun, careful to not apply too much. I then dip my finger into denatured alcohol or water and smooth the caulk wiping away any excess. Smooth again, pull the tape off, Then lightly smooth any anomalies. (Takes practice to get the right touch)
A photo of the edge may provide info for more advise or for alternatives to caulk.