I’m not sure if I understand you correctly. If you open the hamburger menu ☰ of your NFS filesystem service and then go to Paramters for this service:
… then you will be directed to the ruleset(s) to configure the filesystem levels of that service:
The ruleset is called Network filesystem - overall status and usage (e.g. NFS).
It’s a slightly different ruleset than that for the “regular” filesystems, but is already built into checkmk and requires no extra steps:
