When adding your inputs in Livestream Studio, one source you will notice is your computer's screen. Select this to add a local screen capture as an input.
Note: This feature is ideal for systems with multiple monitors connected (e.g. Livestream Studio one one monitor, and PowerPoint on another monitor). Please note that local screen capturing will increase CPU.
Save your settings to see the screen in your multi-view. You can transition it into Program the same as with any other input.