| MichaelCullen |
From the getting started section of the CRB under common terms:
CRB wrote:
Damage Reduction (DR): Creatures that are resistant to harm typically have damage reduction. This amount is subtracted from any damage dealt to them from a physical source. Most types of DR can be bypassed by certain types of weapons. This is denoted by a “/” followed by the type, such as “10/cold iron.” Some types of DR apply to all physical attacks. Such DR is denoted by the “—” symbol. See Special Abilities for more information.
You would be hard pressed to explain how trample is not a physical source. So yes DR should apply.