She was working as a medical assistant when she met German film director Hans Billian and started a relationship with him. In 1975, she acted in the first German hardcore full-length feature film, Bienenstich im Liebesnest (soft version named Im Gasthaus zum scharfen Hirschen, also known as Zimmermädchen machen es gern), directed by Billian. She played Graziella Schill, a woman pursuing her older husband who cheated on her. In this film she does no hardcore; her most explicit sexual act is giving a brief footjob to a man. Actually handjob at the end.
In 1976, Billian gave her the title role in Josefine Mutzenbacher...wie sie wirklich war? (Sensational Janine), the film that earned her great fame in Germany. The film was about the early life of Josephine Mutzenbacher until she became a professional courtesan. In this film, she has sex with ten men (eight in the shorter German DVD version), including Frithjof Klausen who plays her stepfather, except two on whom she performs only fellatio and/or handjobs. Josefine's age is given as 14 in the novel but is mentioned as 17 in the script for the film.
In 1977, she starred in Kasimir der Kuckuckskleber. She played Larissa Holm, a "fun-loving" young woman who agrees with Kasimir Zwickelhuber (played by Sepp Gneißl) to prostitute herself for her debts. Although her role in this movie is smaller than her role in Josefine Mutzenbacher...wie sie wirklich war?, she performs in three different sex scenes and has sex with five men.
In this period, Rhomberg also performed in numerous hardcore loops directed by Billian. Her scenes in loops such as Venus in Seide and Schwarzer Orgasmus were among the first examples of interracial pornography on the German porn scene. She also worked as a fluffer for the Billian films. She played a hooker in the film Heiße Löcher, geile Stecher where she has sex with 5 men, which was apparently shot before Josefine Mutzenbacher...wie sie wirklich war? or even before Bienenstich im Liebesnest, but was released much later.
In 1978, she broke up with Billian and returned to her original profession. She later settled in Switzerland.