I'll agree with Charles in that you will find people that swear by paste and some by hone but the rounding issue he talks of is not an issue if you are using a paddle strop.

The rounding issue is if you use paste on a hanging strop. On a hanging strop over time you will probally round the edge some do to the give in the hanging strop. No matter how taut you hold a hanging strop it is meant to give atleast a little so it makes it easy to slightly round off an edge. However the paddle strop gives you a nice smooth/ridged surface to work off of just like a hone does.