1. Make sure you have a document opened.
    For Illustrator script, if you select a text object, the script will only be applied to that object. Otherwise, the script will be applied to all text objects/layers in the active document.
  2. From Photoshop menu: File > Scripts > Browse...
    From Illustrator menu: File > Scripts > Other Script...
  3. Select the downloaded script file and click “Open”.
This is how Thai text looks when there is no tracking.
Bonus! Adding Actual Spaces

If you want actual spaces between text, you can do it here. The spaces will be inserted at the right point in Thai text. Please note that this method with break the line-break detection for the text.

Space Type