Originally an opt-in Wikipedia Gadget, Reftoolbar was moved to a site-wide script on February 25, 2011, and to an opt-out gadget on April 2014. It comes in two versions, depending on the settings at Preferences → Editing → Editor.
Click on the version number for more information about each refToolbar implementation.
The RefToolbar style column indicates the widget that activates the cite mechanism.
Before 2017, there were three versions of Refoolbar: 1.0, 2.0a and 2.0b. Version 2.0a was removed on June 14, 2017, since it was no longer needed.
Then you are using the rich-text visual editor. It also has a Cite button, with an auto-filling citoid service, but that one is NOT RefToolbar. If you want to learn how to use that Cite menu, please refer to the Visual Editor user guide.