Hi - I'm trying to convert resize and export RAW image to a jpeg for my website. In the export box I've tried adding dimensions at 1000 x 667 but the resultant keeps doing up as 834 x 667.
It sounds like you have cropped the image in Lightroom to 834:667 proportions.
Exporting will not change the proportions, since it would distort the image.
So if you want 3:2 proportions in the exported image (1000:667 equals 3:2), the image has to have these proportions before you export it.
What is the Aspect Ratio of the original image and have you cropped the image at all.
If you crop the image first using the 3:2 aspect ratio in the crop tool, then all you have to do is export the image with 1000 pixels on the long side and you should have exactly what you want. But you need to crop the image to the proper aspect ratio first.