Mac OS X Server 10.3: Can‘t add a third-party package to NetBoot image

Learn how to add a third-party (non-Apple) package to a NetBoot image.
Symptom

When you try to add a package to the NetBoot image, Network Image Utility issues these alert messages:

Solution

When adding non-Apple pkgs or custom-created pkgs, take one of these actions:
Published Date: Oct 7, 2016