This article explains the use of surfaces with the Load Transfer stiffness type in RFEM 6. A practical example is also provided to demonstrate the application of self-weight, snow load and wind load to a steel hall.
More about RFEM 6:
https://www.dlubal.com/en-US/products/rfem-6/what-is-rfem
New features in RFEM 6:
https://www.dlubal.com/en-US/products/rfem-6/new-features
Download the free trial versions and get to know the new RFEM 6.