To enable the feature it is required to activate the 'ICMS-ST presumed tax' checkbox in the Brazilian parameters form, tab Fiscal document.
It is also required to select the NT version on the Fiscal establishment settings (available for NF-e 4.0). At the moment of release, the latest value is '2018.005 v 1.20 technical note'. Note: with this setup, changes introduced in 2018.005.v.1.30 are also supported.
Afterwards, following fields are added in the Fiscal document line details: Presumed tax amount, Presumed tax base amount, Presumed tax rate, Presumed FCP tax amount, Presumed FCP tax base amount, Presumed FCP tax rate and filled in with values based on the incoming document upon posting.
It is important to make sure that the 'Final user' checkbox has a relevant value in the Customer account (Fiscal information tab) in order to get the required tags populated in the outgoing NF-e.