Apple - Standard Function keys using External Keyboard on 2016 Macbook Pro (touch)

At least in Sierra 10.12.3, the Keyboard panel of System Preferences has a check box for that which says:

Use F1, F2, etc. keys as standard function keys on external keyboards

When this option is selected, press the Fn key to use the special features printed on each key

This may not apply to everyone, but in my case, I am using a Logitech Keyboard (K750). The Logitech control panel has an override to use the F-keys as standard function keys.