Yes it is a basic switching circuit can be used on RST no problem, despite what the drawing says SPST relay will suffice, this just means single pole ie just controls the live(or earth if you want, but only one) single throw ie goes on or off nothing else.
The drawing points to a SPDT relay which it isn't!!, it is infact changeover relay.
Just forget the "87a" and get a relay with the other numbers, although the changeover relay will work perfectly with 87a, just trying to clear a little confusion.
The 87a is there as it changes over from outputting from 87 to 87a or vice versa hence it's name.
tabetha