targuy is right if the hot and cold mat are even but if the joint is in an invert or onthe crown of the road its a little differant. inverts are very hard to roll without leaving roller marks. start by pinching just 2 inchs or less then move to the hot mat androll with the edge of the rollerin the center of the invert. this is not real easy so go slow. weve found if your roller operator is making alot of marks its sometimes easier to run your platetamper perpindicular across the joint while its hot this will remove most of them. a joint in the crown of the road is easy as long as your screed man doesnt have his head up his ass. we always run the center of the drum rihgt on the crown this puts the most weight on the joint. we never vibrate the crown as it will smash the aggragate and turn the joint white. the inspectors in pa frown on that. i hope this helps you out. the best way to learn this is like everything else, try differant techniches and do what works best for you with the conditions your in [roller type, weather,etc] good luck
