The RTP are the graphics from the engine, and they are needed to play the game you made - because without the pictures, they have nothing to display on their monitor.
And there are three ways to get the pictures to your friends:
1) you can include the RTP as is by the checkbox when creating the archive, increasing the download size by more than 200 MB.
2) they can download the free RTP installer from this site (that is not the same as the entire engine, and they don't need to purchase the program to get the RTP) - this is preferred by many because they only need todownload RTP once and can then play any game made with it.
3) you can use the description in the locked topic you found to include only the minimum neccessary pictures from RTP in your game - this will require you to put several hours more work into your project in order to reduce the download size of your friends - and they would still need to download the free RTP whenever they want to play other RM-Games...
Why can't your friends download the RTP? Are they on a bad internet connection?
Edit: The link given above was defective, here's the correct link:
http://www.rpgmakerweb.com/download/additional/run-time-packages
Make sure they download the correct RTP for the Maker you've used