Finally, if you zoom in far enough, the frequency, city and state will appear. Regardless of zoom factor, each transmitter location should show up as a little box. Mac I don't run a Mac, nor have I had any reports from people who do. However, I suspect the instructions for Windows will be very similar for Mac users. Operating instructions should be identical.
Most data comes from the NOAA list, nwsli.list.
For stations not in this list, the geographic location for the listed city was obtained from the US Census Bureau's Tiger Mapping Service. Completeness Location data for NOAA Weather Stations has been entered for all locations in nwsli.list . However, some stations exist that are not in that list. These have to be individually looked up and are done as time becomes available. As noted above, the geographic location that is used is the location reported by the Tiger Mapping Service.