The final step for this fastener is to install the backing plate and bend over the four tabs that hold it all together. The backing plate is slightly crowned and also has a dot stamped in it. Position it with the crowned side toward the fabric, and the dot on the same end as the top half of the fastener.

I like to use channel lock pliers for this task, because I can squeeze the fastener together, and bend and crimp the tabs down flat in short order. The long jaws also have a fairly long reach over the edge of the fabric. Again, if you're worried about damaging the shiny surface of the fastener you can place something softer under the jaws of the pliers.