What I understand,
Normally the accuracy check is done as comparing the the NAVAID DME with calculated distance (i.e the distance on ND to that NAVAID).
E.g if the difference is less than 1 NM, RNP 1 is assured.
Note states that an alternative method can also be used: That is comparing NAVAID radial (i.e VOR Radial) with calculated Bearing (i.e the bearing on ND to that NAVAID). However this time, the bearing and NAVAID radial difference can be acceptable as long as this difference is within 1.2 times of the required RNP. For example if RNP 1 is required, the radial and bearing difference may be 1 x 1.2 = 1.2 degree.
If you ask me "is this practical ?".
Of course not at all, but this is Airbus.