Currently, it is possible to add up to 4 live streams in Producer. 

How to add a live stream:

1. Press the '+' button on the layer you wish to add your live stream - If you will be adding any assets on top of your live stream we suggest you add your live input to the bottom layer

2. In the window on the right-hand-side select 'Live stream'

3. Input the title and source URL

4. Add source