Anti-freeze leak

I own a’92 Ford Taurus which is leaking anti-freeze. I have put sealants in the radiator twice which makes me think it’s the resevoir at fault.

Is the resevoir necessary; can’t I simply top up the radiator as needed?

Those sealants very rarely work so I would in no way rule out the radiator. You’re going to need to physically find where it’s leaking from to do a proper diagnosis. Are you getting puddles of antifreeze under the car?

Most of the time, after use

GreasyJack is correct - you need to just find the leak. If it turns out to be the radiator you can likely get one from a junk yard. But there are lots of places it can be leaking from.

You can’t remove the reservoir b/c it is part of how the whole system works - when hot the system gets under pressure - at certain pressures (usually 15-16lbs) the radiator cap lets coolant run out to the reservoir. If you remove it, you’ll end up dumping hot coolant all over as you drive.