Subdirectory install on Mac, new sites get 404

I’ve just done a fresh install of 3.8.1 on my old MacPro, running MacOS 10.7.5. I put wordpress in my user/Sites directory, so I access it as scutaro.fid/~jerry/wordpress. I set it up as a network install, subdirectory option. Works fine for the “main” site. Then I add a second site, with site address ‘newsite’, which now shows up on my site list. But, when I try to get to its dashboard so I can import an existing site, by selecting the “dashboard” jump from the Sites panel, I get a 404 error, “The requested URL /~jerry/wordpress/newsite/wp-admin/ was not found on this server.”

There is no such directory created, but maybe there doesn’t need to be. I’m not sure how this is supposed to work. I’ve included the .htaccess in my wordpress direcory, and it includes the following:

RewriteEngine On
RewriteBase /~jerry/wordpress/
RewriteRule ^index\.php$ - [L]

# add a trailing slash to /wp-admin
RewriteRule ^([_0-9a-zA-Z-]+/)?wp-admin$ $1wp-admin/ [R=301,L]

RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(wp-(content|admin|includes).*) Users/jerry/Sites/wordpress/$2 [L]
RewriteRule ^([_0-9a-zA-Z-]+/)?(.*\.php)$ Users/jerry/Sites/wordpress/$2 [L]
RewriteRule . index.php [L]

What is my next step to figure this out?

Thanks, in advance, for any help!