In an ideal world, a bed iron is installed as shown in figure 1.

Important points to note:
The downside of the ideal installation is that in most applications the bed iron, and box spring, shows below the rail. To avoid this problem, many people opt for this alternate installation:

Notes on this alternate method (figure 2):
Convenience. Need something you cannot find in our catalog? Check our handy list of things we don't make and where to get them. Still can't find what you want? Contact us and we will do our best to help, and we will gladly send you to another supplier if they have what you need.
Horton Brasses Inc., 49 Nooks Hill Road, Cromwell CT 06416, 800-754-9127