How to add a specific ammount of force along a vector?

[Mulbin]

I'm trying to accelerate an object towards another using a specific ammount of force.

I have the vector towards the object, how do I now apply force along that vector AND set the ammount of force?  Simply using the existing add force - Vector function gives you no control of how much force is added (in fact it appears to just add an amount that matches the vector degrees whch is pretty weird).

[Mulbin]

Bumping this as I've never found a solution.