Resources for workload

Hi,
I would like to set up a board to see the future workload in my upcoming project in various dimensions. for example - each project is a group in the board and for each task I would like to put in the number of certain type of employees require (i.e. planners, assembly line workers etc.).
I tried using number columns so I can use decimal numbers but when I did a workload dashboard I couldn’t assign the number columns as resources for the workload. Ideas?

Thanks,
Yaniv