First rset line should be a “header”, e.g.:
rset id 'n1' Title 'Support 1'
Then it is followed by the items you want to gather in the set, e.g.:
rset id 'Px' Set Node Item Px No 1
rset id 'Py' Set Node Item Py No 1
rset id 'Pz' Set Node Item Pz No 1
Then when you use ella/maxima on the set you get the max/minfor an item AND the accompanying values.
E.g. Max Px yields
Py when Px is max
Pz when Px is max
The main purpose of rsets is to get accompanying values of items that are not co-dependant in the model.
Combinations on a beam for instance will give you the maximum moment with the accompanying shear.
This is not as straightforward for e.g. support springs. The vertical and the horizontal spring are two different elements, so you can “connect them” with a set.
You seem to be using it as a workaround instead. So either you create one set for each node or you clump them together into one set.