In order to follow signals in the Bible and Faithlife mobile apps, you must ensure that a few things are set up correctly first.
One key thing to keep in mind when setting up and using signals is that signals are broadcast to a specific location; they are location based, not group based.
1) In the Proclaim application, your presentation must have the location set to the correct address. The address is located in a dropdown on the main toolbar. This is the location where your signals will be broadcast.

2) In the mobile app you are using (Bible!, for example), you must have "Follow Presentations" set to "On". This is located under "Account" (the little gear symbol) > "Settings" > "Follow Presentations".
3) If you have never followed a presentation by a particular group before, you will also want to have "Ask to Follow Nearby" set to "On." This will ensure that when the presentation goes On Air, the Bible app will ask you if you want to follow it.

Once you have followed a presentation by a particular group, they will be placed in the "Proclaim Groups" list. In future, whenever a presentation from that group goes On Air, you will automatically start to follow it. If you no longer wish to automatically follow presentations by that group, you can tap the group name and select "Forget this Group".
4) If you are still unable to see the signals or presentation, check to ensure that you have location services turned on for your phone. You can ensure that your device is at the same location specified on your presentation by opening the Maps app and checking to see the locator pin is at the same location as in the Proclaim application.
5) If you are running iOS 6, you will have to explicitly set the location services for Logos Bible app and/or Faithlife app (whichever you use to follow signals) to "On". You can do this by going to Settings > Privacy > Location Services. Ensure that the switch for Faithlife and/or Logos Bible is toggled to "On".