How do I draw in a pdf with preview smoothly (Even freehand tool seems not good enough)

Preview has strong capability of viewing, editing and annotating pdf files, but it seems to actually "draw" in a pdf is not that smooth (in which I mean even by using the free hand tool. I was trying to find ways to do it since I will be going to graduate school, and I suppose there will be lots of stuffs to read and take notes.)

Free hand tool

The problem is: after each stroke, there will be adjustable corners that impedes you from drawing the next stroke smoothly (which is quite annoying).

The only way I can think of now is open my parallel desktop and run a windows-version onenote, and then import the file and then draw. But it seems to be too arduous if I have to do it every single time (And by doing this you won't get a separate pdf file that has the content you wrote in).

So does anybody know if there is a convenient tool to do it (or is there any way to customize the free hand tool to disable the automatically appearing corners)?Thanks a lot.