Rydberg lines are narrow band as Rydberg atoms have long live times. On the other hand attosecond pulse is extremely broadband. It will surely match lots of transitions at the same time. In particular I expect that high-energy wing of the spectrum of attosecond pulses would simply ionize the atom as the ionization energy is very close to Rydberg levels. Of course you have to compare the pulse spectrum with the levels of the specific atom.