How to add a custom PHP page to phpBB3

There is a tutorial explaining how to add a static HTML page, with phpBB header and footer.

This is how to add a dynamic PHP page in a similar way:

1. Go to ACP | General | Security settings, and set "Allow php in templates" to "Yes".
2. Follow the tutorial at: http://wiki.phpbb.com/Practical.Add_custom_page
3. In the template (e.g. about_us.html), replace where it says "Content in here" with <!-- INCLUDEPHP relative/path/to/your/php/page.php -->