Wrestling with a rambunctious ram to put on a harness is not the easiest of jobs but ensuring the harness is properly fitted can help avoid situations like the one below.
When using a marking harness make sure it is correctly fitted to the ram. An improperly fitted harness can cause chafing of the under arm area of rams who have little wool cover in this location. The friction between the strap and the animal can rub the skin raw. In the photo above the harness became loose, allowing the straps to rub on the animal.
Rams typically lose weight during the breeding season. The combination of exercise and lack of food consumption (they have other things on their mind) reduces the ram's girth causing the straps to loosen. Harnesses can also loosen over time as the straps work their way into the wool.
Check a harness for proper fit during the season. This can be done when crayons are changed or when the flock is brought in to document new crayon marks. The harness should be tight to the rams body and exhibit minimal movement. Don't forget that the crayon also needs to be positioned between the legs.
(Note: The ram in the above photo was treated with topical applications of Iodine and Pinetar.)