error BC31429: 'ApplyForce' is ambiguous because multiple kinds of members with this name exist in class 'FarseerPhysics.Dynamics.Body'.
There are two methods named 'ApplyForce' on the class FarseerPhysics.Dynamics.Body.
They have the following signatures:
public void ApplyForce(ref Vector2 amount);
public void ApplyForce(Vector2 amount);
As the source code of FarseerPhysics.dll is not part of this CodePlex project, the class Spritehand.FarseerHelper.PhysicsSprite should have one or two "facade" methods to call those important methods.
For example, add in the PhysicsSprite class:
public void ApplyForceToBodyObject(Vector2 amount)