And which type of bar code will you use?
There are two parts to this:
a) installing a bar code font and
b) if the type of bar code requires it, computing a "check digit" to include as part of the bar code
What calculation to use for b), if any will depend on the specific bar code you want to employ and you can usually web search on the type of code you choose to use to find out what calculation needs to be used.
So if you set up a calculation field to take an auto-entered serial number from a field set up for that purpose to add with that "check digit", you then need only format that field to use the bar code font and you have a bar code that you can print.
For sample scripts on how you might use a USB connected scanner with FileMaker Pro, see: Need help writing script to integrate barcode scanning
I'm open to the type of bar code I need. The only thing I do know is that it shouldn't be a QR code since I think it would take up too much space to print. My list will potentially contain thousands of names.
What I would like to make the bar code from an alphanumeric field that contains 12 characters that are unique to each person (this field is already in my solution and has been generated for each person). I would like to scan with an iPhone, have a confirmation screen show up with the person's name and address, and push a button to say they have arrived.