  We study the distribution of local magnetic susceptibilities in the
two-dimensional antiferromagnetic S=1/2 Heisenberg model on various random
clusters, in order to determine whether effects of edge disorder could be
detected in NMR experiments (through the line shape, as given by the
distribution of local Knight shifts). Although the effects depend strongly on
the nature of the edge and the cluster size, our results indicate that line
widths broader than the average shift should be expected even in clusters as
large as $\approx 1000$ lattice spacing in diameter. Experimental
investigations of the NMR line width should give insights into the magnetic
structure of the edges.
