Rsyslog config files are located in: /etc/rsyslog.d/*.conf
Rsyslog reads the conf files sequently, so it is important that you name your config file so that the specific config is loaded before anything else happens. So, name your file starting with leading zero's, i.e. 00-my-file.conf (It's better to create a new file so that updates and so on doesn't overwrite your local config).
if $programname == 'programname' and $msg contains 'a text string' and $syslogseverity <= '6' then /var/log/custom/bind.log
Or if you just want to discard certain entries:
if $programname == 'programname' then ~
In your case: (UDP)
if $programname == 'programname' then @remote.syslog.server
if $programname == 'programname' then @@remote.syslog.server
The & ~ means to stop processing matching (previous line only!) entries further.
Some more general info:
Also, always make sure filters are on the same line:
# Example: Log mail server control messages to mail-queue.log
if $hostname == 'titus'\
and $programname == 'smtp.queue.'\
and $syslogseverity <= '6' then /var/log/titus/mail-queue.log
More info: http://wiki.rsyslog.com/index.php/Configuration_Samples