An incident meter will always take an average of what its sensor sees. Ideally that should be the same as what the camera lens sees. It's the intended use of that type of meter.
Now, what you do with that reading is something else entirely. You can intentionally over-expose or under-expose your film, and you can intentionally under-develop and over-develop it too.
I use the incident meter always with the dome pointed to the camera. Like Mark says, if I point it to the light source, you will not average what the camera sees, and it will not be consistent. Brightness range varies from scene to scene to scene, the light source could be of varying strength. The only consistent way of using the incident meter is to point it towards the camera to get an AVERAGE of what the camera lens sees.
I'm sure that there are other ways than my way to use the meter, and I'm not saying it's wrong to do so. But, I wouldn't want to try to keep track of brightness range of varying lighting scenarios with an incident meter. I was sure that that was what spot meters are for...