The ornamental design for a rectalinsert, as shown and described.
FIG. 1 is a top perspective view of an ornamental design for a rectal insert;
FIG. 2 is a bottom perspective view thereof;
FIG. 3 is a front elevation view thereof, the rear elevation view, the right side elevation view, and the left side elevation view being mirror images;
FIG. 4 is a top perspective sectional view thereof, taken along a section line A-A in FIG. 3;
FIG. 5 is a front elevation sectional view thereof, taken along a section line A-A in FIG. 3;