Total posts : 45366
From your user name I conclude you are an amateur radio operator. You therefore are capable of reading and understanding the FCC part 15 rules regarding FM. What is not obvious from the rules is that the power delivered to the antenna to produce a legal field is approx. 11 nanowatts. This is one nine millionth of the .1 watt that you cited.
The field strength limit (there is no power limit) is very restrictive in terms of range. If you decide to use the tx. you described, you will have to demonstrate, if asked by the FCC, that your station meets the requirements. With the power levels you mentioned, this would require effective shielding of leakage from the transmitter and a very high attenuation of the ouput signal before the antenna as well as documented use of a valid field strength measuring device.
As was mentioned, the responsibility for compliance with the FCC rules rests with the operator and not the manufacturer, as it is on the ham bands. Gather all the information you can and make an informed decision.
Be very careful with this.