supervisor of the thesis. The supervisor agrees with you upon the topic and is your direct contact person over the elaboration period. The second reviewer is involved into the agreement upon the topic, but will [...] elaborated at the end of the Bachelor, Master or other studies. The following aspects can be considered when preparing for it. As a rule, you need two reviewers, the main reviewer also being the supervisor [...] mind that the intended topic should be in synchrony with the working and research topics of the desired reviewers you want to contact. As a rule, you will have to elaborate an exposé after the first orientating
https://www.isd.uni-rostock.de/en/isd/studium/study-progress/final-thesis/