1. Open Plug-ins Manager.

2. Double click on plug-in Import RTF Files, add ;*.php to supported formats. For example: Rich Text File(*.rtf;*.txt;*.c;*.cpp;*.h;*.ini;*.pas;*.sql;*.php)|*.rtf;*.txt;*.c;*.cpp;*.h;*.ini;*.pas;*.sql;*.php

3. All others text files can be supported by Wim Document Keeper in this way.