Follow the instructions on installing your mantel at https://rusticahardware.com/instructions EXCEPT you will need to be sure you add 1/8”–1/16” to the distance between the bottom of the mantel and your floor to allow for some clearance so that the surrounds will fit under your mantel when installed.
Step A: Anchor supplied face mounts to your wall where you want your surrounds to sit under your mantel. Install one set just below the mantel and one set along the floor
Step B: Slide your surrounds over the face mounts. The mounts should rest nicely in the grooves inside your surrounds.
Step C: See top view below.
Step D: Finish by screwing in the supplied grabber screws through the pre-drilled holes in your surrounds to secure them to the face mounts. Repeat for the face mounts installed along the floor.