Asus RS100-E4/PI2 - Manual (Page 40)

Chapter 3: Installation options 3-6
11. Secure the server to the rack with
two rack screws.
Rack screw
10. Carefully push the server all the way to the back until the front panel
fits the front end of the rack, and the rack screw holes on the server
match the middle hole on the rack.
Rack screw
hole