Born in Langenfeld, Germany, Rathgeber was influenced at an early stage by Sesame Street and The Muppet Show which were broadcast on German TV. After school, he studied Communication Design at the Los Angeles Art Center's College of Design and worked in the advertising and game design industry. In 1992, the Jim Henson Company sought German puppeteers to work on the production of The Secret Life of Toys, which was to be produced in Duesseldorf. Rathgeber, Jurgen Tombers and Marcus Hübner were three out of 40 puppeteers who finally got the job.
“I was thrilled! There were Dave Goelz, Jerry Nelson and Louise Gold sitting around a table as I walked in the studio's kitchen. And I was to work with them for 6 months, nearly every day - what a great experience!”
For some years, Rathgeber was a puppeteer for the German version of Spitting Image and was also involved in puppet building and designing. He now lives near Karlsruhe, Germany and has his own creative studio working for entertainment and television companies.