How I can add new field on standard RF Screen in EWM

Hi experts, I have an enhancement to add a new field on screen of the RF. So I have a manual packing process and when I press function F3 for mobile list details values about the process, in this screen I want to create two field that will be filled with a owner logical. So somebody has some document or tip how can I do it . I'm trying to do by RF Frame Work , where I create a new step , but the system doesn't find my function during execution and because of this I can't fill the new fields.