Brake fluid on rear wheel

[RMT1983]

if its on the wheel I would say its coming from the caliper or the pipe............... everything else would be too far forwards for it to leak on to the wheel.

Check the bleed nipples, then the banjo bolt, then the seals around the pistons.................

If its the seals then probably best bet would be to change the caliper for a 1000 blue spot. If that's the way forwards you want to go give me a shout as I have one for sale