i typically use about half a cup in a gallon bucket, fill up half way ( i figure the more dawn in water mix, the better ) or just a bit more.
When filling, use hose on half or you will end up with 3/4 suds and 1/4 mix lol. you want more mix than suds ( but suds work also )
Since i have a slight sadistic attitude toward fire ants, i usually stir up the mound and poke several deep holes, wait for them to swarm.
Pour.
Lawn chair to view the carnage.
I usually do two buckets like that. Sometimes ill even come behind the pour with hose/jet nozzle and suds up the ground as much as i can.
Oh and it does not harm your lawn either.