BIND9 & Recursive Clients

[ptselios]

Hallo,
I have bind-9.3.6 from RHEL 5.8 and
snmp-5.3.2.2

I want to monitor the number of recursive clients, polled each minutes. The number of recursive clients is displayed from rndc status. I just don't know how to add that information on my snmp.conf file.
Currently, I have added the following line:
pass .1.3.6.1.4.1.2021.55 /usr/bin/perl /usr/local/bin/bind9-stats-snmpd.pl
in order to have the bind statistics.

What do I need to do?