Social Login & Social Sharing by Janrain
Requires PHP 5.2 (with JSON) or newer and WordPress 3.1 (The plugin is all new please test it before deployment on a live site.)
Copy the 'rpx' directory and its contents to your
/wp-content/plugins/ directory or use the plugin installed built in to WordPress.
Activate the Janrain Engage plugin through the 'Plugins' menu in WordPress
You will need to allow user registrations. Go to General Settings and turn on "Membership, Anyone can register."
Visit the Janrain Engage configuration page by going to 'Settings' -> 'Janrain Engage' and follow the instructions to finish your installation. If you don't already have an Engage account and API key, you may click Get a Janrain Engage Account Now to sign up. If you have already created an Engage account and site for your WordPress blog, just enter your API Key into the box and click "Save."
Due to the new email address requirements in WordPress 3 users will be prompted for an email address if the provider does not deliver one. If the provider settings does not show email as a profile option the plugin will require the user to enter an email address.