bind RIP protocol to specified address

[Ivan]

Hi all.
I use bird2 (2.0.7) on linux, I want to configure the RIP protocol so 
that it uses the specified source address. I have two addresses assigned 
on the network interface, for example 192.0.2.1/32 and 198.51.100.1/31.
bird chooses 192.0.2.1 as the source address, but I want the source 
address to be 198.51.100.1.
How do I set the source address for the RIP protocol ?
Thank you.