Originally Posted by Kazekan

Yes it does...

"Sacred Shield: When a paladin casts Flash of Light on a target with this buff, they also now place a heal-over-time effect on the target, healing that target for 100% of the Flash of Light amount over 12 seconds."

All you need to do is cast FoL on the SS'd target to proc a HoT. The only thing a crit does for you in relation to the HoT is increase the power of each tick due to the increased healing of that particular FoL, up until another FoL lands in which case the HoT is recalculated. This ability does not work like an Ignite where you can create rolling damage (or heals in this case) to increase the effect by proccing it more than once while the buff is still active. If it did, that would make it way too powerful, considering by the time your first HoT timer ran out, you would basically be rolling a 5500HP+ HoT on the target, just by spamming FoL for those 12 seconds (assuming ~1.1s FoL cast time and 500pt avg HoT ticks).