The following "KeyCaps" charts show how to produce special characters with the Hobogirin font for Macintosh. You can see and test the key combinations yourself by using KeyCaps (or as here on the Japanese system "kii hairetsu").

* macron o is produced by holding down option and shift keys and typing o
* macron o is produced by holding down option and shift keys and typing u
* macron U is produced by holding down option and shift keys and typing ; (semi-colon)
* macron O is produced by holding down option and shift keys and typing / (back-slash)

* with the option and shift keys held down

* with the option key held down

*with the control key held down

Note: screen pictures taken with the shareware ScreenCatcher for Macintosh.
(Users of Windows might try HyperSnap-DX from Hyperionics.)