Source patching in Adobe Premiere Pro is a feature that allows you to control which source tracks in your project are targeted for editing. This can be particularly useful when you're working with multiple audio or video tracks and want to ensure that your edits are applied to the correct ones.

To use source patching, first, open your project in Adobe Premiere Pro and locate the source patching indicators in the timeline panel. These are represented by 'V' and 'A' icons for video and audio tracks respectively. Click on the 'V' or 'A' icon for the track you want to target. A highlighted icon indicates that the track is targeted for editing. Now, any edits you make will be applied to this targeted track. If you want to target multiple tracks, simply click on the 'V' or 'A' icons for all the tracks you want to target. Remember to unselect the icons when you're done editing to avoid unintentional changes.