I know this topic is old, but I'm posting the newest process for this, since it took me hours to figure out.
1.
-Open the Houdini Launcher
-In the Install the Labs/Packages tab, install the LabFX "Production" version that matches your version of Houdini.
2.
-Open Houdini
-Inside your geometry node, add the Soften Normals node
My nodes
3.
-Export your object as .fbx (not available in Houdini Apprentice), or you can save your geometry as .obj
For fbx: File > Export > Filmbox FBX
My fbx export options
For obj: Inside your geometry node > right click the node you want to export from > Save > Geometry
-Be sure to add the .obj at the end or it will not save as obj
-There are no save settings for obj (that I could find)
4.
-Import your File into Unreal
-You should get an FBX import window. I don't know what is important here for the smoothed normals, but here are my import settings:
Note: For obj import into Unreal, the same FBX import window will show, but I changed the rotation and uniform scale to be this:
-It also doesn't have much info in the "Fbx file information" section of the import window.