I recently decided that i would like to utilize Observium as well as rancid for configuration backups on my home network. To that effect, the following links really helped me out getting it all setup correctly:
https://docs.observium.org/rancid/
http://packetsandpings.blogspot.com/2013/05/installing-and-configuring-rancid.html
https://layer77.net/2016/08/10/upgrading-from-rancid-2-3-8-to-3-4-1/
Let me know if you run into anything i might help out with.
/Kim