The ornamental design of an under shelfsignholder, as shown and described.
FIG. 1 is a perspective view taken from the front, top, right side of the under shelf sign holder showing my new design;
FIG. 2 is a front elevational view of the under shelf sign holder of FIG. 1;
FIG. 3 is a back elevational view of the under shelf sign holder of FIG. 1; and
FIG. 4 is a right side elevational view of the under shelf sign holder of FIG. 1, the left side elevational view being a mirror image thereof but otherwise identical;
FIG. 5 is a top plan view of the under shelf sign holder of FIG. 1; and,
FIG. 6 is a bottom plan view of the under shelf sign holder of FIG. 1.
The broken lines show features of the under shelf sign holder that form no part of the claimed design.