Add Avertisment To Posts and/or Pages?

[cfisher 0]

I place an advertisement (468x60) via javascript at the bottom of each post and/or page. I currently manually add it to the _posts.php which works fine; however, I have to remember to re-add it with each template upgrade. Is there a better way?

[cmunns 16]

for pages and single post pages you could use the content sidebar, but to have it show up on the bottom of each post on the main blog page it will have to be in _posts.php as you have it.