Copy the rpx directory and its contents to your /wp-content/plugins/ directory.
Activate the rpx plugin through the 'Plugins' menu in WordPress
Visit the RPX configuration page by going to 'Settings' ->
'Options,' and follow the instructions to finish your installation.
If you don't already have an RPX account and API key, you may click
the "Get an RPX API Key" button to kick off the automatic configuation
of your wordpress installation. If you have already created an RPX
account and site for your WordPress blog, just past your API Key into
the box and click "Save." That's it!