best way to monitor a processes RAM usage?

[Skrell]

I've been doing various google searches trying to understand the different memory units windows gives us in the task manager for process' memory and have failed to find a clear way to see an individual process's RAM usage.  Is there a recommended way to do this perhaps using ProcessLasso's metrics?   
My ultimate goal is to figure out why the System process spikes in disk usage periodically and I'm thinking it has to do with running out of RAM and having memory paged out repeatedly.  This then causes the entire PC to freeze up for a second or 2. 
Any suggestions/thoughts?
This is Windows 8.1 btw.

[Jeremy Collake]

No single memory metric is perfect in all cases, but normally one would use Private Working Set.

The Resource Monitor (resmon.exe) is great for this type of thing.

If memory load is the issue, you'll see your system RAM load persistently above 70%, and you will see spikes in hard page faults (see ResMon Memory tab).

[Skrell]

No single memory metric is perfect in all cases, but normally one would use Private Working Set.

The Resource Monitor (resmon.exe) is great for this type of thing.

If memory load is the issue, you'll see your system RAM load persistently above 70%, and you will see spikes in hard page faults (see ResMon Memory tab).

This was very helpful thank you!