|Building The Network You Need With PF, The OpenBSD Packet Filter: BSDCan 2016, Ottawa, Canada, June 8th 2016|
OpenBSD: version 5.5 and earlier: All relevant options are enabled in the GENERIC kernel. For newer versions, please jump to Traffic Shaping with Queues and Priorities.
No further configuration (outside of pf.conf) necessary. But note that you will need to convert away from ALTQ for traffic shaping on OpenBSD 5.6 onwards.