Depending radio buttons

I have a complex form with a lot of elements. One element section cares about the visibility of the dataset:

  1. Unlimited
  2. Limited

This is realized with radio buttons of course, where unlimited is the default selection.

When "Limited" is selected, some more options are shown to the user. Beneath the typical discussion (hide vs. disable - which was discussed here a lot) I wonder what is the best design to show that form elements depend on the selection of other elements.