How can I render an object with subdivision surface, without actually subdivide it at the geometry level? I searched for a while and the closest thing seems to be "Render Polygons As Subdivision" option, but it's for Mantra only. Is there an equivalent of this for Karma?

If you bring your stuff in via scene import, it's enough to tick on "Render as subdivision surfaces" on the OBJ side.

If not, you can use an Edit Properties LOP for example, and set subdivisionScheme to catmullClark.

And/or

https://www.tokeru.com/cgwiki/index.php?title=HoudiniLops#Enable_subdiv_on_poly_meshes [www.tokeru.com]

• Append a mesh edit lop
  
• Set the prim path to your mesh
  
• Enable 'set or create' on subdivision scheme