Hi!
I've got a question regarding free drops from immovable objects. Do you have to mark your ball before you pick it up? I think yes but I was told you don't have to do it, and I can't find the correct ruling in the Rules.
I know that the Pros are always marking their balls.

-Mr Mizuno

I don't think you have to mark it. Generally, you only have to mark your ball if you are required to replace it, which you are not going to do in that situation.

I'm thinking it doesn't hurt anything to stick a tee in the ground where the ball was. Whether required or not, I don't know. I think I would put a tee where the ball was, put another tee at the point of nearest relief, and then a third tee at the boundary of where you can drop at. Only takes a second to do this. That way there are no questions. btw is it one club length or two, from the point of nearest relief? I'm constantly forgetting. Isn't it two clubs from a hazard, an unplayable lie, a cart path, and an immoveable object?

Usually it is one club if there is no penalty stroke, 2 if there is a penalty. So 2 from a hazard and unplayable and 1 from cart path and immovable.

Don't think it's required to mark, but it isn't a bad idea to, so you have good solid reference points.
I beleive the "proper" way to do it is to mark the ball (I don't even touch the ball until I'm 100% sure I want to take the drop) mark your nearest point of relief, then mark the 1-2 club lengths away no closer to the hole.

That way you now have original point, and acceptable drop area (nearest relief and club lengths) for first ball contact....from that point the ball is allowed to roll up to 2 clubs away provided it doesn't get nearer to the hole.

So in theory you can get up to 3-4 clubs of relief with the drop.

Under the Rules the player don't have to mark the ball unless it has to be replaced, but it's always IMO a good idea to mark it if possible.