If that's not yet a part of Directadmin, you as always have a choice: hope and wait for an official release or do it yourself. So that's it. If you need it now, just add it manually; if you want to see it implemented into Directadmin, then you should report either a bug or a feature request.
Please make sure you've got all DNS templates updated and actual, as it might be already there. I haven't either tested or checked it.