You should be able to use most linear barcode formats with PerfectTablePlan and a USB barcode scanner. We recommend the code 39 format (also known as 3/9), which is the one we have tested most.
A standard PerfectTablePlan guest ID (15 characters + 2 asterisks) requires approximately 50 mm (2 inches) when printed with a code 39 font big enough that it can be reliably read by a barcode scanner.
You can get a free barcode 39 font from BarcodesInc. There are also commercial vendors such as IDAutomation and Elfring Fonts.
For more information on barcode formats and fonts see the excellent barcoding fonts site.