You should be using the x10 setting, and getting something like this, running rail to rail (so ~5v Pk-Pk)
The reason the 'x1' setting rounded-off the appearance is that the clock is being loaded with the scope's input capacitance (usu. 15pF) directly, and that of the probe cable. In fact at 'x1' setting the probe will only have a usable bandwidth of about 5-6Mhz, and so the scope effectively displays a low-pass filtered result. Even at 'x10' the display isn't quite right, because the clock isn't driving a matched impedance (50ohm input) on the scope, and because the probe only has a bandwidth of 50-60Mhz or so (as in the chaep + crappy one I used above). With this it can only show the first 5 harmonics, not enough to show a clean squaewave and leaving significant ripple on the display waveform
...
But don't worry about it. Actually seeing what the clock is really doing is not so simple at all. Even a scope with adequate bandwidth, and suitable probes to allow you to exploit it (expensive!) will tell you nothing about the resulting sound. In fact the key parameter that a 'good' clock addresses, jitter, is the variation in timing between pulses, and you'll
never see this on a scope. For the TentLabs module the specified jitter would represent an average variation in the position of the vertical lines above of just about ... 1/30,000 the width shown above.
Given the oscillator is chopiing between the rails at high speed and driving current into the load (and scope probe..) it should be no surprise that the supply rail carries noise at clock-related frequencies. This high frequency noise which get everywhere and can only be controlled by passive components (principally, the tiny SMD ceramic cap underneath the Flea board across the clock module pins).
0.15v sounds reasonable if a touch high (10-20mV can be achieved); but - again- don't worry, this could be due to something as simple as picking the wrong place to put the ground clip, the length of cable on the ground clip, using too wide a bandwidth setting (if your scope has one) and so on. Scopes are great fun, but remember they lie all the time...
A really good primer on getting the most out of your scope is Tektronix'
XYZs of Oscilloscopes. HTH!