If you would like to request a new font be added to the Font Picker, you can contact Shopify Support and Gurus can file a feature request.
Shopify's font picker settings have been introduced in the following versions of our themes: Mobilia 5.5.0, Parallax 3.5.0, Retina 4.5.0, Responsive 6.5.0, Turbo 3.1.0, Artisan 1.0, Flex 1.0.
When updating to these versions using the Theme Updater App, you will need to reconfigure your Typography settings (the default is Open Sans). This unfortunately is unavoidable as we cannot directly map the old method of choosing a font with the new font picker option in Shopify.
An extensive, standardized list of typeface options is now available, with previews of the typeface visible within the 'Customize' settings editor found under Online Store > Themes > Customize > Theme Settings > Typography.
Please note: using the Rubik font may result in display issues on Windows/Android devices.