You can follow the below steps to add the angled dimension without centerline.
You can look below sketch and I need to add angled dimension between the angled lines mentioned in screenshot with reference to horizontal reference. But horizontal reference line is missing here.
Instead of creating manual reference line, you can select smart dimension and Select inclined line and followed by corner point like below. You will get quadrant like below.
Then select the horizontal quadrant line and it will give you the angled dimension that you want.
After you follow above steps and still you need assistance feel free to contact our support at email@example.com or (65) 6372 1416.