It's possible in theory, but depends on the weight of your magnets.
Our force sensitive resistors have a working range between 0.2N and 20N (in practical terms, they can weigh objects between 20 grams and 20 kilograms). We have a tutorial that explains how to use them here: http://learn.adafruit.com/force-sensiti ... r/overview
If your magnets are sufficently heavy, you should probably be able to see a change in the resistance of the FSRs beneath them.
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