I can get RSZ_KB and VSZ_KB stats from sourcetype=ps (and from top also but in different fields). These both values don't give us exact stats about how much swap space each process is using.
Here is the method I am using to calculate that on my Linux host:
grep Swap /proc/[1-9]*/smaps | grep -v '\W0 kB' > /tmp/swap1.out
sort -n -r -k2 /tmp/swap1.out > /tmp/swap.out
So now I can see in "swap.out" how much swap space each PID is using.
Can Splunk add a script to calculate swap for each PID in *NIX app or elsewhere?
You can add that script to your own instance of the unix app yourself, run extensive testing, and then feed that script back to Splunk for inclusion in a future version.