[itsm] Create CI with a field from OTRS users

Hello How can i create a field on a CI related to OTRS users? All my users are to be responsible for the CI's and i would like to link them into the CI I can link to customers like this code below, but i'm unable to do it for users. Key => 'Responsavel', Name => 'Responsável', Searchable => 1, Input => { Type => 'Customer', }, Regards Hugo