I'm wanting to type some Pinyin characters (e.g. adding a
bar above an
Alt A + A) and am following this guide http://pinpinchinese.com/blog/how-to-type-pinyin-tone-marks-mac-os-x-yosemite/
However, I don't see the option of a US Extended Input source. Here's what I do see:
Fwiw, I'm running El Capitan 10.11.2 (15C50).