Depends on what you hope to achieve with the strop. If you're just looking to clean up some light burrs from your edge, or gently re-align a rolled wire edge, a bare strop can work just fine. If your goal is to further refine, hone and/or polish the bevels, some compound would be a good idea. All of this depends on the edge being ready for stropping, too. If the edge isn't very sharp to begin with, or not fully apexed, a strop of any configuration probably won't help too much, with compound or not. Most of the real work needs to be done on the stones first, and stropping shouldn't take more than maybe 10-20 passes (or less) to really make the final edge 'pop'.