The meter on the SR-955HPC can be used just like an external SWR meter. It will not lower the SWR; it only shows you what it is. You then take that information and decide if you need to raise or lower your antenna to achieve a low SWR.
Sometimes people get the meter confused with an Antenna Tuner. Antenna tuners work by matching the radio's impedance to the feedline's impedance which connects to the antenna.