RTK requires one receiver to act as Base, and one to act as Rover
The Base sends corrections to the Rover, to fix the Rovers Position
The Base does not need to fix, it needs to know its location to calculate error for making corrections.
Corrections from the Base can be sent to the Rover by Lora radio, or over the internet using NTRIP.
It sounds like you are using your RS+ in “Averaged Single” base mode.
It is normal for the precision to be in meters in Single mode.
To increase the precision, you will need to add another factor to your setup.
You could use another receiver to calculate corrections, as @PotatoFarmer suggested. This would be an “RTK” workflow.
You could alternately use a “PPK” or “PPP” workflow to establish a more precise point.
I agree with @PotatoFarmer and Dave. Standalone Reach RS+ has only several-meter accuracy. You need a pair of receivers to obtain accurate coordinates in RTK or PPK. Regarding PPP, with Reach RS+ you will get an accuracy of about 30 cm because it’s a single-band device.