If you want to add a management fee to a portfolio, you can do so when you create or edit a portfolio.
To add a fee to an existing portfolio, click on a portfolio from the client page, and select "Edit"
Once the Edit window pops up, you can add a fee at the portfolio level in the Fee % field. This is the same window that you will see when creating a new portfolio.
You can also edit management fees in bulk across multiple portfolios at once using Edit Portfolio Group. You can access this by clicking on the household and selecting Edit as with the portfolio edit. You can click the Settings icon to get to the Fee field.