Adding iZotope Plugins into FL Studio

Install your iZotope plugin from the Splice desktop client. If you choose a custom installation destination, take note of the file path.

Once installed navigate to FL Studio go to:

Options
General
Manage Plugins

On the left, you can add plugin search paths, add the location you installed your iZotope plugin into and hit Start scan. 

Nectar 3

RX 7

Vocalsynth 2

Neutron 2 / Ozone 8