How do you rotate inserts in Apple Mac OS preview 7?
You can rotate inserts and annotations, like text boxes, rectangles or signatures, by arbitrary angles:

Hold the Command ⌘ key and rotate the selected annotation with two fingers on a trackpad. 

As far as I know this only works with trackpads and is undocumented. It works on macOS High Sierra.

This is from an apple communities question: How can I rotate the text box in Preview