Vertical tab widgets follow the same core structure as the regular tab widgets. (you can find the configuration setup here)

The only difference is that you have to add and additional class on the parent HTML Widget and where the parent HTML widget lives.

Configuration:

1. Add an HTML widget to a page and press Edit in the upper right-hand corner.
2. Switch to the Appearance tab and copy & paste ps-tabs tabs-style-vertical into the Class dialog box.
3. Drag & drop at least 2 widgets underneath the parent HTML widget.
4. Go to the Appearance tab of each widget and copy & paste ps-tab into the Class dialog box.
5. Name the tabs by entering a unique Title on the Options tab of each child widget.
6. Publish the page.

*The RSS Feed widget is not compatible with Widget Tabs