Sauerstoff -Upload -Schriftart

Click "Use Any Font" (its a free plugin install it before)  in the WordPress admin menu

Click "Generate Free Lite / Test API Key" and then click "Verify" (or add your API key if you have one)

Go to the "Upload Font" tab and click "Add Fonts" on the right hand side

Give the font a name, select the font file from your computer and click "Upload"

The added font now automatically appears in all Oxygen's Font Family lists.
Jesús Angarita