When you create the custom field group, you select Contact, and then click anywhere and you should see a field pop in to view re 'multiple
See 
And once you have added the Fields too, then you should see something like 
on a contact record. (Grabbed before demo gets flushed)
When you create the custom field group, you select Contact, and then click anywhere and you should see a field pop in to view re 'multiple
See
When you create the custom field group, you select Contact, and then click anywhere and you should see a field pop in to view re 'multiple
See
And once you have added the Fields too, then you should see something like on a contact record. (Grabbed before demo gets flushed)
When you create the custom field group, you select Contact, and then click anywhere and you should see a field pop in to view re 'multiple
See
