In order to stream with your phone camera, at this moment the easiest way would be  integrating a LiveReacting plugin into a software that allows streaming with a phone. 

Or, there is an alternative workaround, so you can emulate you phone camera as webcam using a software like EpocCam

Check out how to setup EpocCam here

After you successfully installed EpocCam software, you just need to:

• Add a Camera Layer to your project in LiveReacting Studio
• Click on a drop down menu on the left bottom corner
• Choose EpocCam as a camera source