Adobe Reader

How do I configure Safari to use Adobe Reader as the default .pdf software?

right-click (cmd-click) a PDF - "Get Info" - "Open With . . ." change the drop down from Preview to Acrobat Reader.

Preview is much better than Adobe's reader IMO but to each there own.

As an aside, if you mean whether a pdf open inline in the browser that depends on the version of Safari you have.

Prior to 5.1 you could enter the following into a Terminal window:
defaults write com.apple.Safari WebKitOmitPDFSupport -bool YES

Since 5.1 it doesn't seem to work and you'll need something like TinkerTool

Yes. I want to use Adobe Reader for online .PDF's while in Safari. I have it setup as my default reader. I am in V5.1
I prefer the printing tools and the toolbar icons in Adobe vs. Preview.

I was under the impression that this was set in Adobe Reader. I don't have it installed at the moment but IIRC, you could set this by going to Adobe Reader > Preferences > Internet.

Looked at Adobe settings. The "Display PDF in browser using: /Applications/Adobe Reader.app" is checked, but it is in phantom.

I rebooted and checked a PDF in Safari and it is not using Adobe.