Yes
and
No
The rating on the actuator is technically the minimum boost you can run. However this rule of thumb assumes the wastegate is capable of flowing enough to support the base boost pressure.
If you install and properly setup a 15lb actuator on a stock turbine housing/wastegate port it WILL over boost as the wastegate will not flow enough to bypass suffcient exhaust gas pressure if opening from 15lb.
Rule of thumb #2 is you should run a wastegate base spring pressure of aprox 1/2 your desired boost pressure. Again this assumes sufficient wastegate efficiency, but this may not give you the best turbo response. So a well ported wastegate (or external gate) and slightly higher than 1/2 spring rate will give you better response but also flow enough to control boost.
All of the above assumes your intake and exhaust are also up to the task, so without know current mods/setup and what you're planning it difficult to give a definitive answer.