Asus RS300-H8-PS12 - Manual (Page 48)

Chapter 3: Installation options 3-4
Do not install the rail kit in the following situation:
DO NOT place the rail hook on a thick lip of the
mounting hole.
DO NOT install the rail to the outer side of the
server rack.
7. When mounting the server to the rack,
ensure to include the side knots on the
two sides of the server in the rack rail
holders.