ds layouts in FAPI forms?

i want to override my contact form. i followed this tutorial: https://www.youtube.com/watch?v=rSgd91tZSEc

i have enabled ds_forms but there are no ds layout options on the contact site form as shown in this video at 9:20. layouts only available in entities (and nodes).

any ideas how i may activate layouts for code generated pages like contact forms etc.