The ornamental design for an R/F curtain panel, as shown and described.
FIG. 1 is a perspective view of the R/F curtain panel showing my new design, installed in a typical unclaimed environment;
FIG. 2 is a back elevation view of an exemplary individual unit of the claimed invention shown for illustrative clarity, all individual units are identical, and collectively form the R/F curtain panel;
FIG. 3 is a top plan view thereof;
FIG. 4 is a right elevation view thereof;
FIG. 5 is a front elevation view thereof;
FIG. 6 is a left elevation view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines in the drawings show unclaimed environment only and form no part of the claimed design.