[keycloak-user] Custom regstration flow

Hi, I am Daan Zwaenepoel, A last year student ict. For my student job I have to intragte keycloak into a angular app. What I already did setup the keycloack sever, making the link to the angular app, start a custom theme and the login flow works. My next task is to build the registration page and  make it work. The last point is where i have been stuck for a while. In the keycloack base regastration flow you have the base fields username,firstname, lastname,email,password and password-confirm. Now the point where I have been stuck, In our registration we have one more field and I dont no how to add this costume field to the flow. Is there anyone who can help me or give me tips by buidling this custom registration flow? Thanks! Daan