Plate Rail

I have the rail but I know the best way to fix the false front without the brackets to the poster. it runs about 25 feet around the other side of the kitchen and therefore must be cut, which poses no problem. the rail we purchased has no meaning for the installation and I wish he looks as professional as possible when I'm done.
Thank you!

Are you sure it is called rail plate "? Could it be Rail Gallery? (See link below for reference)
If this is Gallery Rail, it is usually nailed to the box with small finishing nails.