A lot to be said for RTFM....page 45 of my manual, also on the back of the card insert that has all the shortcut commands....clearly states what F8 does.

If the PDF is not available in the DLC version, they do have the manual online (it's under Playguide at POL site), which tells you about the /targetnpc text command at least (didn't see the Fx keys when skimming it). It's also in countless guides online, possibly even in the new player tutorial videos linked over at the FFXI site (basic controls has a section on targetting). You can also download a PDF of the manualsfrom the support portal as well (hint: it's the big button labeled "Instruction Manual" when you click the support link from POL). It's right there on page 2 of the quick guide (only 2 pages to it).