What size of O-Ring and bore hole would you recommend for mounting the ILPS28QSW sensor wather tight?

[SBroc.1]

..

[allard.potma]

See documentation for the lps28dfw, application note: AN5937

[Nick Alexeev]

AN5937 indeed has the dimensions for the o-ring (see Fig. 3).  1.8mm inner diameter, 0.5mm cross-section diameter.

But here's a snag: the smallest standard cross-section diameter is 1mm (from these tables). 

Who makes the appropriate non-standard o-rings?  Please post the suppliers and the part numbers.