protocol://hostname:port/… all must match.
So if you set your site domain is: https://example.com, then your Wordpress has to be set to the same domain and protocol. If for example, your Wordpress is set to https://www.example.com it will not work, as it breaks the rule above.
Stacks 4 or above
WordPress (installed at same site/domain)
For a seamless experience the headers and footers of the Wordpress site theme should be disabled. Some themes have that option available at the theme customizer in the Wordpress dashboard.
I recommend the BLOCKSY theme, as it's free and very customizable, without the need to edit it by hand. You can easily turn off the headers and footers, customize the fonts, layout and buttons to match your Rapidweaver site design.