The ornamental design for a rim for a sink, as shown and described.
FIG. 1 is a top perspective view of the rim for a sink;
FIG. 2 is a top plan view thereof;
FIG. 3 is a cross sectional view taken along line 3--3 of FIG. 2; and,
FIG. 4 is a cross sectional view taken along line 4--4 of FIG. 3 thereof.
The fragmentary broken line representation of counter top in FIG. 1 and the broken line representations of bowl structure in FIG. 3 and FIG. 4 are for the purposes of illustration only, and form no part of the claimed design.