Hint 6 spoiler

So you couldn't find the right file? It's quite logical actually, it's called admin.py and it's located in the website/members directory.

Once you've opened it you should find something like this:

class ProfileInline(admin.StackedInline):
    fields = ('starting_year', 'programme', 'address_street',
              'address_street2', 'address_postal_code', 'address_city',
              'student_number', 'phone_number', 'receive_optin',
              'receive_newsletter', 'birthday', 'show_birthday',
              'direct_debit_authorized', 'bank_account', 'initials',
              'nickname', 'display_name_preference', 'profile_description',
              'website', 'photo', 'emergency_contact',
              'emergency_contact_phone_number', 'language',
              'event_permissions')
    model = models.Profile
    form = forms.ProfileForm
    can_delete = False

That's a lot of field we have here! Fortunately we only need to add one. You should end up with something like this:

    fields = ('starting_year', 'programme', 'address_street',
              'address_street2', 'address_postal_code', 'address_city',
              'student_number', 'phone_number', 'receive_optin',
              'receive_newsletter', 'birthday', 'show_birthday',
              'direct_debit_authorized', 'bank_account', 'initials',
              'nickname', 'display_name_preference', 'profile_description',
              'shoe_size', 'website', 'photo', 'emergency_contact',
              'emergency_contact_phone_number', 'language',
              'event_permissions')

Now you can run concrexit:

1. cd into the website directory.
2. ./manage.py runserver.
3. Test your new functionality!