Go to Portfolio -> Fees/Commissions (found on the lower left side):
You can apply a fee to a whole platform, or just for individual investments:
Fees can be added as either:
> Fixed dollar amounts:
> Scaled percentages:
When using this area, the first two fields ("From" and "to") refer to the investment balance, and the final field defines the percentage of fees to apply at that level.
For example:
