The developer kit ships with 3 beacons, 2 RadBeacon USB beacons and 1 RadBeacon Dot. Configuration is handled via the RadBeacon app, which is available for iOS and Android via the App Store and Google Play.
At the time of writing the iOS version of RadBeacon doesn't discover Eddystone compatible RadBeacons, but Radius Networks confirmed via Twitter that Android was a priority and iOS support is imminent.
The RadBeacon app contains help information that describes how to put the USB beacons into configuration mode though it doesn't currently describe how to achieve this with the RadBeacon Dot, fortunately this article on Radius Networks' support site describes the process (thanks to @CraigTaylor74 for helping with this via Twitter).
I had a few false starts configuring the beacons, and found the RadBeacon app didn't always recognise the RadBeacons, initially listing them as "Unspecified Beacon". We're close to day 1 of Eddystone availability though so the odd quirk is to be expected.
I was soon able to get up and running and after configuring the URL property of the beacon and applying the changes the beacons were happily chirping away and transmitting Eddystone-URL frames.
The quickest way to interact with your new Eddystone-URL service is to download Chrome for iOS and enable the Today widget. See this post on the Chromium blog for details.
David G. Young has detailed the full process over on the Radius Networks' Developer Blog, work through the process as described (take note of the tip on using a URL shortener) and you can't go far wrong.