I'm no expert on remote masses (I use remote loads/forces mostly) but if you right click on "External Loads" you can choose the option and attach the remote mass to a surface, edge, point on the needle as required. If you have a cylinder, for example, and you are clamping on, say, one end, you may need to split the surface to give you the appropriate 'landing space' for the remote force.
what do you want to learn in this analysis?
I will place a rigidbody on the top plane of my needle. If the rigidbody is too heavy, my needle will get deformed.
I want to know the maximum mass that my needle can support in order to design the rigidbody and choose a good material for the rigidbody.
Jared Conway is the Analysis Service Manager in largest VAR of USA. He can provide the information you need.
Please engage him for the consultant service.
deformation > fea
rigid body > motion
if you need to combine both of these, you'll need to go to a nonlinear dynamic analysis
my suggestion would be to look at each separately at first before you go to a more complicated analysis type