As previously stated, so long as the impedance is 50 ohms, and the wattage (ie: 2 watts) exceeds the capability of the transmitter then there is no problem.
Note : you can make this pretty easily... all you need is a 50 ohm, 2 watt resister. Then solder it to the connector of your choice. I have several 5 watt 50 ohm resisters, each with a different type of connector.
firstname.lastname@example.org =========== It takes an Act of God to fade a wireless path, but any fool with a backhoe can cut fiber ==========
Like Dennis said the 50ohm impedance is required and the wattage is the factor that you have to watch.. as long as the wattage is higher than the maximum transmit power all is good... Dennis' idea is a great one, probably cheaper than a factor termination for lab purposes.