Heroku Service - Specify Your App Name
Today we deployed a change to how the Heroku one-click service works. Heroku recently released their European region, and with that change they deprecated the "proxy" subdomain for Heroku apps. To make DNSimple's one-click service compatible with this change, we now require your Heroku app name, as it appears in your herokuapp.com subdomain. When you add Heroku just enter your app name part of the herokuapp.com domain and you should have an ALIAS for your apex domain and a CNAME for "www". You can always add or change these later.
Anthony Eden