1. Add Countries to the Raiser's Edge
  2. Log into NetCommunity as an Administrator
  3. Click on Administration > Code Tables
  4. Click Refresh Code Tables button
  5. Click on Administration Sites and Settings
  6. Mark the checkbox for countries that you wish to appear in the Countries section on the page
  7. Click the Save button at the top of the page
The countries should now be showing on the form.
These steps apply to any forms in the NetCommunity website, include Online Admissions or Online Reenrollment. 

Additional Resources
Changing the order that countries appear in NetCommunity.
Wrong country showing in plugin for transactions