Hi Bernhard,
Welcome to our community!
As @mark1st.john mentioned above, a Base/Rover setup will be more accurate.
A standalone GNSS receiver can only determine the position to within 2-4 meters accuracy without any corrections, whereas a Base-Rover configuration will give you more precise centimeter accuracy.
If you still would like to configure RTK with only one receiver acting as a rover, I can suggest an NTRIP service. This way you do not need to have your own local base. To work with NTRIP, you need to ensure the availability of the internet.
We have a post dedicated to obtaining precise coordinates with just rover.