The floor 3/8"x3" engineered over plywood

Here it says to use a NO. 5 trowel

http://www.stauf.info/a/DataSheets/WFR- ... %20mastic'

I have been to Home Depot and Lowe's and can only find something close to the NO. 4 size.

Will the NO. 4 be okay to use in my application?

Thanks!

I have never seen a proper notched trowel at HD or Lowe's, for wood flooring.

3/16x1/4x3/16 Is usually the recommended trowel for 3/8 strip, if memory serves me correct without going out and looking at a bucket.