Hey, sorry about that. Better read them-there rules then, 'ey?
Here are my ideas, as this is just an explanatory type answer, with no calcs, I'll just write my idea, it seems logical to me, but I am thinking I may be missing a big, obvious, glaring flaw in it...
Idea:
a possible answer may be to add ONE molecule of the radioisotope of the SCN- and then do repeated analysis of the two sides of the equation, (ie. test the aqueous solution or the CNS- precipitate) to see which side contains the radioactive bit, and observe that while the concentration of the two species is remaining the same, the radiocarbon atom is moving between both sides while in equilibrium.
Is there a flaw with this idea?