1. Ensure the Commenting toolbar is visible (View->Toolbars->Commenting)
  2. Click Stamp tool (Stamp tool icon) button in the toolbar.
  3. Click anywhere on a page to add a stamp of default size or click+drag to create a stamp of a custom size.
  4. To choose a different stamp:
    1. Click and hold the black triangle on the Stamp tool (Stamp tool icon) icon to reveal the menu of available stamps.
    2. Choose Built In-> to see the selection of pre-defined stamps
  5. Double-click the stamp to open its associated note window.