Reddit employees, also known on Reddit as “Admins”, support sitewide issues, whereas moderators manage subreddit-specific issues. The button to look for to send a message to the moderators of a subreddit looks slightly different on each platform.
Go to the right-hand sidebar and search for the envelope icon in the “Moderators” widget
Go to the right-hand sidebar and search for “message the moderators”
Visit the subreddit page, and look for the overflow menu () > Message moderators