Proza Libre is the cousin of the commercially released Proza typefamily by Bureau Roffa. http://bureauroffa.com/about-proza It's made to render exceptionally well on screens across different operating systems.
A short screencast about the process behind Proza Libre, using ttfautohint: https://vimeo.com/140530738
Proza Libre was made with:
Fontlab Studio V
To generate webfonts yourself simply:
Generate a ttf from the vfb file in Fontlab
Download and install the latest version of ttfautohint. http://www.freetype.org/ttfautohint/#download
Use the Control Instructions File in ttfautohint to generate the hinted ttf
Use any webfont generator to convert the ttf to webfonts.