Put planner-rdf.el in a directory that is in your Emacs load-path and the following into your ~/.emacs file:
(require 'planner-rdf)
(eval-after-load "muse-publish"
'(progn
(add-hook 'muse-after-publish-hook
'planner-rdf-publish-file)
(add-hook 'muse-after-publish-hook
'planner-rdf-publish-index)))