types of resistors and inductance
In order to observe a clean square wave at 200kHz, the rise-time needs to be around 250ns (about 10% of the pulse width). The sparkfun tutorial shows the clock coupled through a 10k resistor. Now, to get 250ns risetime, you need an RC time constant of 114ns giving a capacitance of about 11pF. So the sum total of the circuit input capacitance, the stray capacitance and critically, your 'scope probe capacitance must be less than 11pF. I reckon this is your problem.

If the waveform looks OK at the driven end of the resistor and the input capacitance of the driven device is low, you might be OK but you won't be able to prove it without a very low capacitance 'scope probe.