I am mocking up a Mac App interface on El Capitan and would like to use the San Francisco system font. However the San Francisco font doesn't appear in Photoshop's font menu. Is there a way to access the system fonts in Photoshop?
It seems that Apple has intentionally locked down the default system font.
However you can download a development version of the font which you can install in addition to the system version. It has tight licensing restrictions, mockups only, but that's all I needed it for, so this solution worked well for me.
More detail can be found on Ask Different.