If you want to check profile-wise (cumulative info with all VS's) you can run show ltm profile rewrite <profile name> CLI command and see if it has matches. This commands returns matches in a "counter" form.
If you need to dig deeper into a specific VS, the same info should be available with the show ltm virtual <name> details CLI command. [EDIT: this has LOTS of infos on all profiles, so I'd recommend appending the | grep "Rewrite Profile" -A 20 syntax (where 20 is the number of lines to be shown) to only match the info you need ]
It's a counter as I said, so you'll probably need to check it a couple times --let's say after a week or so, depending on how often this service is contacted-- to check if it had increased.