Hi,

You can make that checkbox appear by adding this to your user.config file:

<add key="ShowLegacyOpenIDSelector" value="true"/>

then touch Web.config to make it reload settings.

However standard Open ID is not very user friendly, very few users even know what it is or what its for or how to use it. Instead of that I highly recommend enabling the Janrain Social Login which is much more obvious and user friendly. 

Hope that helps,

Joe