We have migrated the Radiance functionality to a measure, which will be fully documented when we release OpenStudio 1.9.0 at the end of September. Basically, all you need to do differently is add the "Radiance Daylighting Measure" to your model. This measure is included as of version 1.8.4 **, and can be found in the measures library, under Electric Lighting --> Electric Lighting Controls --> Radiance Daylighting Measure.
By adding this measure to your model, OpenStudio will behave as it used to when you selected the "Radiance" radio button on the run tab; your daylit spaces (i.e. those with an illuminance map and one daylighting control point) will have the annual daylighting simulated with Radiance, and the lighting load schedules for those spaces remapped to the available daylight, and passed to the EnergyPlus model.
Apologies for the abrupt disappearance of the selection buttons, and the lack of docs. We are working on it. In the meantime we'd love any feedback on the new measure!
** I recommend you use the latest iteration release (1.8.5), as it does a better job of including and locating the necessary versions of Radiance and EnergyPlus on your system.
