Rats typically use attics for shelter and raising young. They spend their other time foraging for food outside of your home and returning for shelter after they are well fed. They are continually moving in and out of homes on a regular basis. So think of it this way, rats use your attic as a hotel while everywhere outside is their restaurant.
I have learned that they are especially fond of mandarins and orange sliced jellied candy. So a simple way to check for rats is to offer them something special in a place very easy to find. Take two to three small pieces of either a mandarin or an orange slice candy and place them in areas of your attic you suspect the rats may be found. Check your bait every day or two and if it disappears, that may indicate you have rats. If you suspect rats, don't panic. They're very common in Florida.
To confirm your findings, call a pest service to come out and give you a free, through inspection.