I must pressure my register page to https, and permit other pages to become looked at using https or http (e.g., http://www.example.com/signup should redirect to https://www.example.com/signup). I could pressure all pages to https, but cannot get just one page to redirect to https. The page just loads normally as http.

Here's the code I have been attempting to use within my htaccess file:

RewriteEngine On
RewriteCond %{SERVER_PORT} 80
RewriteRule ^/signup(/.*)$ https://www.example.com/$1 [R=301,L]

For which it's worth (just in case there's a conflict I am not aware of), I'm also while using following code to pressure all pages to redirect to www and also to drop the .php in the file names within the URL:

RewriteEngine on
RewriteCond %{HTTP_HOST} ^([a-z.]+)?example\.com$ [NC]
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteRule .? http://www.%1example.com%{REQUEST_URI} [R=301,L]

RewriteEngine on
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME}\.php -f
RewriteRule ^(.*)$ $1.php?/$1

Any ideas on which I am doing wrong?

Have your https rule such as this:

RewriteCond %{SERVER_PORT} =80
RewriteRule ^(signup/?)$ https://www.example.com/$1 [R=301,L,NC]

Keep in mind that there's no beginning slash / in RewriteRule.