Adding force to a projectile? (SOLVED)

Hi,
I am relearning how to Unity… I left it for about two years, and I now have the motivation once more to get back into it! Happy days. Anyway.
It’s been a while, as you can see… I have forgotten many things… One of which I can’t seem to find an answer that works.

That is my reason for coming to you today.
How do you add force to a projectile, so that it moves towards the (AI Controlled, in my case) player when it’s fired from the turret.

Irony is I can remember how to make a complex AI character which decides its movements based on raycasting… But I can’t for the life of me crack the code to make the projectile move towards the player(john)… The Aim Target (at) its positioned when John is is range, and visible. Also positioned by raycasting etc.

This is what I have so far (ORIGINAL CODE).

function Fire()
{
	if(canFire) 
	{
	
		canFire = false; 
		
			yield WaitForSeconds(Random.Range(0,2)); // random firing time 
		
		var proj : Transform;
		
		proj = Instantiate(pre, spawn.transform.position, transform.rotation);
		proj.rigidbody.AddForce((at.transform.position - transform.position) * Time.deltaTime * 500); 
            // ^ el diablo line 
		
			yield WaitForSeconds(5); 
		
		canFire = true; 
	}
}

WORKING CODE:
function Fire()
{
if(canFire)
{

		canFire = false; 
		
			yield WaitForSeconds(Random.Range(0,2)); 
		
		var proj : Transform;
		
		proj = Instantiate(pre, spawn.transform.position, transform.rotation);
		proj.transform.LookAt(at.transform); 
		proj.rigidbody.AddRelativeForce(Vector3.forward * 500);
		
			yield WaitForSeconds(5); 
		
		canFire = true; 
	}
}

Thanks for you help
-f

For simplicity I would use Transform.LookAt followed by Rigidbody.AddRelativeForce (Vector3.forward). You should not use Time.deltaTime when adding the force. Also, using integers in Random.Range(0, 2) will pick either 0 or 1, which is unlikely to be what you want.