The 'Custom File Dimensions' limits are 4.00 to 100.00 inch at 72 ppi so there's no way to do this in a single step. Use the below Print module settings to create a 3840 x 400 JPEG file and then the Export module settings to resize it to 1920 x 200. NOTE: The Layout> Page Grid> Columns value should be set to the number of images you want to use. I used 4 in the below example.
This can be done in a single step.
First go to Page Setup in the print module and define a page of 19.2 x 2".
Then either create a custom layout or preferably use a template preset to the values you need. In the screenshot you can see I set the columns to six. Populate the template cells with the six images you want. Then use these settings to print to JPEG file.
The final JPEG should be 1920 x 200 pixels.
Here is a link to a Lightroom Template set to a six column layout.
Thanks to both Brad and trshaner. My issue is that I do not have any printer connected as I do not own one :-). when i click on Page Setup in the Print module, i see only print to fax, a pdf file, and one note as options. All the 3 do not have any options to define a page with custom dimensions such as 19.2x2". All I see are A4, A6, Letter, Legal, etc. What am I missing. Do I need to download an epson printer even though i dont have it. If so, what driver do u recommend I download. Thanks.
Thanks to both Brad and trshaner. My issue is that I do not have any printer connected as I do not own one :-). when i click on Page Setup in the Print module, i see only print to fax, a pdf file, and one note as options.
If you have Acrobat Pro installed you can enter a custom paper size as below.
1) Go to Page Setup (CTRL + SHIFT + P) in the Print module and select 'Adobe PDF.'
2) Click on Properties> Paper Quality> Advanced and next to 'Paper Size:' select 'Postscript Custom Page Size' and enter as below.
On my Windows 7 system the output JPEG file is actually 1919 x 200 instead of 1920 x 200. This is probably due to a bug in LR.