FIG. 1 is a front perspective bottom view of the ornamental engagement projection of a retaining wall block;

FIG. 2 is a side elevational view of the engagement projection of FIG. 1;

FIG. 3 is a bottom plan view of the engagement projection of FIG. 1;

FIG. 4 is a front elevational view of the engagement projection of FIG. 1; and,

FIG. 5 is a rear elevational view of the engagement projection of FIG. 1.

The broken lines outlining a retaining wall block are for illustrative purposes only and form no part of the claimed design.