A recent X-ray observation has shown that the radio pulsar PSR B0943+10, with clear drifting subpulses, has a much smaller polar cap area than that of conventional pulsars with mass of $simmsun$ and radius of $sim10$ km. Zhang et al. (2005) addressed then that this new result conflicts with the standard vacuum gap model. Nonetheless, the discrepancy could be explained if PSR B0943+10 is actually a low-mass quark star. It is found that the potential drop in the open-field-line region of oblique pulsars (i.e., inclination angle $alpha eq 0$) might be $sim 10^2$ times that of aligned pulsars, and that PSR B0943+10 with $alpha = 12.4^{rm o}$ could be well above the deathline. We thus conclude that the Ruderman-Sutherland-type vacuum gap model still works well for this pulsar if it is a bare quark star with a mass of $sim 0.02M_odot$ and a radius of $sim 2.6$ km.
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