You may place the lens profile under : C:\Program Files\Adobe\Adobe Photoshop Lightroom 5\Resources\LensProfiles\
Restart Lightroom, it should be there.
There is another folder under LensProfiles named 1.0. That folder contains profiles by brand. I previously placed these user created Rokinon lens profiles into the Nikon folder here and restarted Lightroom, but they never showed up under Lens Corrections in the develop module.... ?????
Could you also place the files in : C:\Users\<username>\AppData\Roaming\Adobe\CameraRaw\LensProfiles\1.0
and then check
The instructions in your first response didn't work, but the instructions in your second response did work! Thank you so much!