Log in to the administrator control panel within phpBB

Select the "Styles" tab from the top left navigation

From the left sidebar, select "Templates"

From the tempalte list, click "Edit" on the currently active template.

From the list of template files, select the file "overall_footer.html".

Copy and paste the Reftagger script immediately before the closing "" tag within the template (located near the end of the file).

Click "Submit".