RMS is a measure of current that the subs can take consistently. The amp will not be enough power for the subs (probably), but you do have to check the specs of the subs first.
The theory goes: Figure out what configuration you are putting your speakers in (parallel or series), and then you'll know what amount of RMS watts your be pumping into your. Example: you have 2x 500 RMS watt subs rated at 4 ohms each. You wire them up in parallel, making a 2 ohm circuit. So now you know you need an amp that pushes at least 1000watts rms in to 2 ohms. The theory on purchasing an amp is get one with 2x (twice) the power than the sum of the rms watts of the speaker. You'll note that the subs can take a peak wattage of 4x the rms wattage. This allows for something called "overhead". Having overhead is good, because it allows for dynamic sound and keeps your speakers running good.
You need to make sure you're not under powering your speakers as that will damage them, more-so than if you over power them. It's kind-of like a car: there is a certain operating temperature that the car works best at...not too hot or cold. Same with speakers. The speakers use the physical movement of the cone to cool the voice coil (the thing that the two speaker wires are connected to on one speaker). If there isn't enough power pushing the speaker, the cone doesn't move much, and then can cool itself enough. This will eventually lead to major damage to the voice coil (which is more harmful to the speaker as a whole than punching a hole in the cone of the woofer...though that isn't good too)
If you have the subs model number we can figure out what you need, just post it up.