At the side or gabels of a roof the drip edge goes over the roofing felt.
Metal roof drip esge over or under felt.
The main purpose of underlayment is to keep water away from the decking if it gets under the shingles.
At the bottom of the roof the drip edge goes under the roofing felt.
On the gable edges the felt paper goes under the overhanging drip edge metal.
Drip edge is a thin metal flashing that is applied to the edges of your roof underneath the shingles.
On the gutter eave edge the felt paper goes on top of the gutter apron drip edge metal.
When the drip edge is being installed along the rake edges it would be placed over the drip edge.
This is done to ensure water runs off the roof smoothly and to protect the decking from exposure to the elements.
Water will pass right under that drip edge.