I'm new to the rigify add-on and I think that I might be struggling with it. I have the armature that comes with the add-on and if I press the generate button it generates a the rig with the root, arms, face... The issue is when I try to pose the rig, the armature doesn't move because the bones of the metarig doesn't have constraints with the rig. I'll upload the project, but is only the rigify add-on loaded.(https://drive.google.com/open?id=1I2CZmrD6FTKLtk5t7MBZP9eYOZQcR6BY). Also, I found the issue in a full modeled model, but it seems to not work on any project. My blender version is 2.79.
The grey bones you see is a predefined armature template riggify uses to generate the actual armature.
The template armature ( grey bones ) are there for you to line them up with your mesh so that when you generate the rig everything is in the right position and you can start weight painting or autoweighting directly.
If you want to see the complete setup you can enable the layers in the armature properties. The bones you start out with can be discarded, these are no longer used beyond the point of generating the actual armature.