By the way, this page is very helpful:
Select the desired font on the left.
Then turn right at "2. Select styles "select the desired font thicknesses (easiest just all).
At "3. Select Copy CSS "only" Modern Browsers "and specify the...
Editor & BB Code Manager
Fully customize your XenForo Froala instance. Change your toolbar layout, enable and disable BB Codes, make use of the new table and background-color BB Codes, provide exciting new fonts for your users from your own server or external hosts. It's all in your...
There is an issue with the Redactor rich text editor used for editing posts. Webfonts linked in the XenForo site don't work in it. The problem is because it uses an iFrame, which is a separate environment and doesn't have access to the loaded webfonts in the main frame.
The solution to this is...
Sick of editing .js-Files to get your fonts into the editor? Sick of them not being rendered in the Redactor but in posts only? Here's your solution: the Fonts Manager. Order your fonts! Create new fonts! All in your hands.
Order Fonts in Redactor Dropdown...