resign if you have black. there's no way to win if you don't have white tbh
How many points down should you resign?

I have been playing a while and was wondering if there is an etiquette for resigning games? I am playing a daily tournament with players 300 - 800 rating points ahead of mine. I am down -4 in one game and probably won't win, should I resign or play it out for the experience?
I am going to give you an answer that probably wont help answer your question much.
Depends...
Depends on your skill level.
Depends on your opponents skill level.
Depends on the position. DO NOT go by "points" Thats to arbitrary.
Depends on how many games your opponent has going. I have played people that have had hundreds, if not thousands of games going at once. Yes...THOUSANDS.
Depends on if its an endgame, that you can learn from.

The very question shows that you should never resign.
Resigning is an advanced skill that should be left to players rated above ~1700 here. Don't worry about resigning. Play every game out to the end, and learn from the technique of your opponents. Or, swindle a draw or win occasionally!
The one thing to remember though, is that if you do play the game out, don't drag out the clock. You don't want to bore your opponent to death. But always be optimistic and look for a ways to save the game!

In a daily tournament unless it's a sacrifice to mate or something like that 4 is to much to over come. Especially if you're playing higher rated players as you say you are. When I am playing someone who is rated 800 points higher than me , often times I will play on and hope to learn something. It's up to you how you want to play it.

The very question shows that you should never resign.
Resigning is an advanced skill that should be left to players rated above ~1700 here. Don't worry about resigning. Play every game out to the end, and learn from the technique of your opponents. Or, swindle a draw or win occasionally!
The one thing to remember though, is that if you do play the game out, don't drag out the clock. You don't want to bore your opponent to death. But always be optimistic and look for a ways to save the game!
I totaly agree! That is how I like to play!! It is disappointing when you are winning the other player decides to resign! You can learn a lot from losing! In fact I learn more when I lose, and then when the other player slips up a little, the victory is even sweeter!
Also I agree with one of the posts above - never resign. Play out the game. I know its bit fun to play a lost position but you never know when your opponent blunders.

Depends on the rating of the opponent too. Yesterday I played a game against someone rated higher than me and found myself in a winning position. For some reason (I'm still really annoyed by it) I then went on to blunder twice and throw away a sure win and only get a draw. If my opponent had resigned as you're asking, he'd never have salvaged that draw - so, if you think you have any chances, or perhaps even you want to use the experience to learn something, keep playing.

should I resign or play it out for the experience?
Play it out for the experience. Unless you really feel there's nothing left to prove. Because remember;

And let's not forget about a recent game from none other then Magnus Carlsen, where he blunders a whole piece on move 17 and wins in the end!

Only resign if the position is truly hopeless. If there is any hope at all for you to come back and salvage something, play it out! You never know, your opponent could timeout, or make a mistake. Especially if he's lower rated than you, play it out hoping that he makes a mistake.

"hopeless"
That's the key word. I recently resigned a single pawn down on another site, but my mobility was restricted and I couldn't find any counterplay whatsoever. Quite frankly, I found the position depressing and I was spending far too long on that game, at the expense of other games, so I resigned. Upon computer analysis, I was a full 3.5 points behind, so it was certainly a lost position, but in terms of pure material it was a pawn.
On the other hand, I can keep going when heavily down in material. If I'm a rook down, but he has a rook that is currently ineffective, then why resign? At least wait until you've exhausted all counterplay.
If you're not sure if you should resign, don't.
I have been playing a while and was wondering if there is an etiquette for resigning games? I am playing a daily tournament with players 300 - 800 rating points ahead of mine. I am down -4 in one game and probably won't win, should I resign or play it out for the experience?