I use 'Level Quik', by Custom Building Products.
A latex primer is rolled over the low surface depressions prior to application.
The leveling material is mixed to the consistency of pancake batter and poured into place. I use long metal straight edges to screed it off.
We used 850#'s of Level Quik, so far.
I need to apply one more 50# batch on Monday afternoon in three areas.
KT