According to the Thai Ministry of Interior in 2000, the flag of Krabi province is yellow with a red rectangle at the hoist on which are two crossed Siamese swords (krabi), as on the provincial seal, with the name of the province beneath. It should be noted that according to Mello Luchtenberg's vexilla-mundi.com website, Krabi provincial flag is now yellow over blue with the provincial seal in the center of the flag.
Adapted from an image found on Arnaud Palac's Cyber-flag website where it was credited to Mello Luchtenberg.
The national flag with the provincial seal in the center.
Description from http://en.wikipedia.org/wiki/Seals_of_The_Provinces_of_Thailand: Two crossed krabi, ancient Siamese swords, in front of the Indian Ocean and the Phanom Bencha mountain, the highest mountain of the province.