Fly fishing with indicators is a lot of fun! Here are a few leader formulas that will work for nymphing with an indicator.

Simple Nymphing Indicator:
Maxima 20lb 0.017" - 36-48"
Tippet Ring/Swivel
Fluorocarbon Tippet - 3-6ft

Tapered Nymphing Indicator Leader:
Maxima 20lb - 48"
Maxima 15lb - 16"
Maxima 12lb - 7"
Maxima 8lb - 6"
Tippet Ring/Swivel(If 3X or smaller)
Fluorocarbon Tippet 2X-6X 3-6ft

Tapered Steelhead Leader For Switch Rods(11ft)
Berkley Trilene Big Game Solar Collector 40lb - 32"
Maxima Ultragreen 30lb - 20"
Maxima Ultragreen 25lb - 16"
Maxima Ultragreen 20lb - 14"
Maxima Ultragreen 15lb - 14"
Maxima Ultragreen 12lb - 10"
Tippet Ring/Swivel
Fluorocarbon Tippet 1X-4X 3-6ft

Indicators I prefer are yarn indicators, oros indicators and airloc indicators.

Go get em!