Writing on video with Apple Pen

I would love to be able to use my Apple Pen on iPad to directly write over clips. Workaround now would be to write on green slide, screen record is, import clip in Rush and chromakey the green out. i would love to directly write over the clips imported, so i know where my written/drawn things end up on my time line. Like a custom graphic effect/overlay thingy. You know, like final Cut has now introduced... 😉