Thanks. I tried to add more relays, but it will not be added to the list after pushing the add button. And yes I checked if it already was in the list and I checked the right url format.....🙋
Discussion
Adding more relays works now. But still I don't know how to add new followers by specifically by its public key. I do not see any option in the user interface in it. For now I can only add new followers via the (global) chat.