This works for both Windows and Mac computers. In the Replace field, type the vowel you want to add a macron to (e.g. "a").In the With field, type the vowel with a macron (e.g. "ā"). A macron is a line above a vowel to indicate that it should be spoken as a long vowel: ā, ē, ī, ō, ū, Ā, Ē, Ī, Ō and Ū. Click on the Windows Start menu and choose settings. Swiftkey allows you to add macrons and spellchecks Te Reo Māori. Learn more about Swiftkey. A macron is a line that appears over Māori vowels, such as a, e, i, o, u. Why is it really important? Gudberlet Fredericka wid Geo h 3920 Llewellyn.