[exim] whitelist senders

Hi,
I am running exim v4.63 and I have created a whitelist hosts file:
/etc/exim/filters/whitelist-hosts

Here is the RBL snippet from my config file:
# Mark it White
warn dnslists = hostkarma.junkemailfilter.com=127.0.0.1
     set acl_c0 = white - dnswl - $sender_fullhost

# Mark it Yellow
warn dnslists = hostkarma.junkemailfilter.com=127.0.0.3
     set acl_c1 = yellow - $sender_fullhost
     message    = X-Warning: $sender_host_address is in a yellow list at $dnslist_domain

# Using the Black List
deny dnslists = hostkarma.junkemailfilter.com=127.0.0.2
     message    = X-Warning: $sender_host_address is in a black list at $dnslist_domain

# Other Blacklists
deny !dnslists = hostkarma.junkemailfilter.com=127.0.0.1,127.0.0.3
     dnslists = zen.spamhaus.org : dnsbl.sorbs.net
     message    = X-Warning: $sender_host_address is in a black list at $dnslist_domain

I want the RBL checking skipped if the sender hostname is in the whitelist file. Can someone tell me what to add to my
config file and where?

Thanks,
Kerry.