I'll be brief...I made this guide for those who don't want to wait for an apk after an update so that you can download it by yourself. You will disguise your phone's country IP as US IP. We'll use Hotspot Shield VPN because it's easy to use and it's free. It will work with any proxy app.
1. Download Hotspot Shield VPN from Play Store.
2. Open Hotspot and click on Start protection.
3. After protection is activated, open your phone's Settings.
4. Go to Application Manager.
5. Click on All to show all your applications.
6. Look for Play Store and then click on Clear data.
7. Open your Play Store and your IP should be disguised as US now.
8. Now you can desactive Hotspot if you want.
9. Look for Ragnarok Valkyrie Uprising and install it.
10. If you can't find the app, open this link in your phone: http://market.androi...com.us.ragnarok
Note: I haven't try it yet because I don't spend money on game, but you should be able to buy rubies from your country using this method.
For those who are too lazy to do this, I'll try to upload APK as soon as possible.
Latest APK v1.2.4 (May 31):