Where the supply line connects to the toilet, the connection is supposed to be finger tight. If that is where it is leaking, first make sure it is actually finger tight and then CAREFULLY tighten it slightly more with pliers. CAREFULY, not too much.
2015 F150 2.7 EcoBoost (Big Spot)
2015 5.0TA (Little Elsie)
"What a long, strange trip it's been....."