To add to what highfigh and Peng said, a speaker's impedance is the total of all it's drivers and crossover through the audio frequency range. Its not a single value, it varies with the frequency.
Below is a graph of the impedance of the RF-7ii. I copied from this link
http://www.avsforum.com/forum/89-speakers/1412510-klipsch-rf7-ii-measurements.html.
The black line shows impedance and the vertical scale on the left side show the ohms values. As you can see the impedance dips slightly below 4 ohms between 100 and 200 Hz. That is where these speakers
might present a difficult load for
some amps. All the rest of the audio range the impedance is higher. However, I wouldn't worry, your amp seems to be capable of easily driving these speakers. (The green shows impedance phase angle in degrees - ignore that for now.)