This read-only Gauge reports the process's resident set size (RSS) in kilobytes, meaning the actual physical RAM it currently occupies. Admins compare this to topProcsSize to see how much of a process's virtual memory footprint is actually resident in RAM, which is a more direct indicator of real memory pressure on the host. For instance, a rising topProcsRSS value for a single process over successive polls would signal to the admin that the process is consuming increasing amounts of physical memory.