Titillium Web is a trademark of Google.
Details
There is an option hrbrthemes.loadfonts
which -- if set to TRUE
-- will
call extrafont::loadfonts()
to register non-core fonts with R PDF & PostScript
devices. If you are running under Windows, the package calls the same function
to register non-core fonts with the Windows graphics device.
Note
This will take care of ensuring PDF/PostScript usage. The location of the
font directory is displayed after the base import is complete. It is highly
recommended that you install them on your system the same way you would any
other font you wish to use in other programs.