use pam as authentication medium of FreeRadius

[Ivan Matala]

i have a server A with freeradius installed. is there anyway to use
the pam of it to be use as authentication medium of freeradius?
(instead of using Auth Type = System, Local, SQL

The pam module (http://linuxexplore.wordpress.com/how-tos/pam-with-radius-authentication/)
connects to another radius server (Server B), and then returns a reply
whether it is valid or invalid.
Thanks