1. Double-click the start of an existing melodic line of music.
  2. Engage Chord mode and Lock to Duration both found in the Notes toolbox.
  3. Chord mode can be engaged using the key command Q, and Lock to Duration using L.
  4. Enter your harmony using either the computer keyboard or a MIDI keyboard.
  5. Use Space to advance the caret; the new notes are aligned to the existing rhythms.