See the exhaust pipe right there? Go up about 3-4 inches...There will be a silver/grey color. That is the rear cylinder exhaust valve cover, oil is most likely coming from there.
If it is, You can ;
Tight down the two bolts or,
remove O-ring, flip O-ring, re-install or,
Buy a new o-ring, replace and reinstall, or
buy a tube of permatex, apply in groove, reinstall.
2013 H-D FXS Blackline
2006 V-Star 1100 Classic
1980 XS650 Bob (in progress)
USMC - 0331 - OEF