The F100 as a general rule is very accurate in the many modes it supports, depending upon the situation.
The difference is the camera is analyzing the exposure through the lens using sophisticated algorithms and you are using a hand held meter to directly measure the light that falls on the scene.
Hand-held meters require knowledge and analytical skills to measure the scene to arrive at the desired exposure for the desired effect. The only way to understand this is to try it both ways...
The F100 is a prosumer (professional/consumer split) camera with many functions, so it is hard to generalize about exposure without speaking about a specific mode.
However, you can effect an overall increase in exposure for one or all rolls of film you shoot by setting your exposure compensation adjustment and leaving it for the entire roll.
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Back to the hand-held meter:
Take the camera in the field with a hand held meter. Put the F100 in manual mode and compare what you get with the camera with what you get with the meter.
If you attempt this with the program/matrix metering mode, it will be difficult to get equal results since you are starting with such a sophisticated camera and the matrix metering does very non-transparent things that will confuse you.
Read up on exposure modes and how they work, but practice in manual mode with the hand-held meter.