What does the abbreviation RKI mean and what are its tasks with regard to self-tests?

The abbreviation RKI stands for the Robert Koch Institute. In consultation with the Robert Koch Institute, the PEI has defined minimum criteria for rapid antigen tests.

Source: https://www.pei.de/DE/newsroom/dossier/coronavirus/coronavirus-inhalt.html;jsessionid=09B536A7388CE2341E5768C21C36E201.intranet231?nn=169730&cms_pos=3