Okay first step you wanna do is open eclipse and make a workspace.
Second you wanna go too the top left corner and click "file" and add java project uncheck "use default location" then find your client on your PC.
Next you wanna click finish.
Now is the best part. You wanna right click the folder in eclipse it should be something like "MY RSPS" then click EXPORT... Then click JAVA... Then JAR...You should see "browse" button now click that and choose the destination of where you would like too place you JAR file, as example in your "downloads" folder. And rename it too "YOUR RSPS NAME" then click next. click next again... Then you should see "main class" and the button for you too browse it... click the browse button! And it should be something along the line of "client" or such. and click that. and then click finish and BOOM you have officially JAR'd your client with eclipse.