When you log in as a regular user, are you seeing a message on the top of the page that portion of the page can be customized?
Is your question about the comment below? You don't want to make an user into a site member but allow them to customize?
By default, site members can make page customizations but non-site members and guests can’t.
If so, have you read the following paragraph?
To allow users to customize a page, administrators must grant users permission to Customize pages under the Site section. This can be achieved by assigning permission to a role, then assigning this role to the appropriate users. For example, if we want any logged user to be able to customize our customizable pages, we could assign the Customize permission to the role User. If we want site members to be able to customize the customizable pages of their sites, we would accept the default setting. By default, the Customize permission is assigned to the role Site Member.
