if you want to say total amount 1000 satoshi/hour
then it should be something like this
1000*24*7=168000 satoshi = 0.00168 BTC
or if it was 1000 satoshi/hour per visitors then it will depends on how much your faucet is popular and how much users it get everyday
Maybe you just budget 0.00168*100 = 0.168 btc for now?
You'd have to consider that it won't get a lot of people right away.
But I suggest lowering your rates. Maybe 500 an hour could be better?