use pam as authentication medium of FreeRadius

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