Posting like this to Facebook, due to EdgeRank, is totally pointless - your content will never get seen as Mr. Zuckerberg and co. will see any third party app. (an external tool or internal Facebook Page add-on) as spammy (like the Poker apps of old) and devalue your posts accordingly. Automation in Facebook means your content is 80% less likely to be seen by your audience. Don't do it.
For some channels (like LinkedIn and Google Plus) it can be done, but the channels themselves don't offer it as a service and (certainly in Googles case) they seem to actively discorage it.
Personally I think all social media posts should be individually crafted for the best results. This should be done 'by the channel', with sympathy to the audience and client goals, and should offer your followers the best experience possible. Yes this is time consuming, but results always are.
Automation for business rarely works well.
Sometimes, however, the client just wants it posted when they publish and to the devil with the consequences. It's not rocket science to fudge this using an RSS feed, but to me this feels almost like grey-hat tactics. In reality, the client pays the mortgage and you can only preach about best practices for so long. This had to be done, so I had to find a simple way to make it happen. If you ever need to do this, here goes.
First set-up a new Hootsuite account for your client. I'm a big fan of Hootsuite. I've written before about creating custom search code for Twitter etc., and once you delve under the hood there's a wealth of good stuff we can turn to our advantage.
Next, on the start screen, click on the option in text at the bottom that says 'Add A Different Social Network'. If you're already logged into an existing account click the button that says '+ Add Social Network', under your list of streams. You'll then get the pop-up, below.
On the left you'll see a list of options - including Google+ and LinkedIn (this process works the same for both, so let's do LinkedIn as an example).
Click on the LinkedIn option, and you'll see the 'Connect to LinkedIn' dialogue.
You'll need to be logged in to your LinkedIn or Google+ accounts already to save any messing about. If you are, Hootsuite will sift through the Pages you belong to and those you Admin. It'll then give you the option to pick one.
Just select the Page you want to post to and click 'Finish Importing' down there on the bottom right.
The next step is to connect an RSS feed. If you have trouble finding the feed there's a good little 'how to', here. If you want to get an RSS feed from your Twitter, I wrote a post about that recently (and that has a whole extra level of potential).
Anyway, just nip back to the main interface (the 'dashboard') in Hootsuite and click on the cog symbol ('settings') over on the left. Then choose 'RSS/Atom'.
Next click on the '+' icon next to the 'My RSS/Atom Feeds' drop down (when you roll over it it says 'Add New Feed').
A box will pop-up with all the fields you need to import your feed and set up protocols. It's pretty self explanatory. Just add the RSS URL at the top, then click in the box that says 'Network to send feed items to' and attach your channel (double check it's the right one, those social channel icons are tiny).
You can leave the scheduling stuff, unless you have specific requirements, but it's good to put something in the 'Prepend text to each message' box to say it's yours and from your blog or whatever. Above I'm just using our agency as an example, I'd NEVER do this for channels I personally manage.
Press 'Save Feed' (bottom right), and Bob's your Uncle.
Remarkably painless, once you figure it out. I still maintain there's no substitute for manually crafting posts, as many of these will be truncated and won't have any call to action or other useful stuff, but if you have to do this I can testify it works.
I feel slightly dirty. I'm going for a shower...