Rose scented geranium (Pelargonium capitatum) is propogated by stem cutting is summer, when the plant is actively growing. Do not use rooting hormone and do not cover the cutting.

Use clean shears or a knife to take a four inch segment of stem from the healthy stem tip of your plant.  Make your cut just below a node (where leaves emerge) as the new roots will develop from that node area.  Remove the leaves from the bottom half of the cutting.

Prepare a clean 2 to 4 inch pot with potting mixture to which some perlite or vermiculite has been added in a ratio of 2:1.  Use the head of a pencil to create a little hole and insert your cutting so that the bottom node is covered. Gently press the soil around the stem. Water well, until water escapes from the bottom of the pot and keep the cutting soil from drying out but not overly moist.  The cutting should be out of the direct sun for the first few days and will begin to root in 2 to 6 weeks.

You can repot in regular potting mixture once the roots fully develop.

Courtesy of NYBG Plant Information