On 500px you have the option of uploading a low resolution photo for display, and then providing a separate high resolution file that will be used only for sales. This allows you to include a watermark on your display photo, while providing a high resolution and clean photo to be used for sales. The high resolution file will never be displayed to the public and will only be sent to buyers after they have paid. Here's how to do it!
1. Upload the low resolution file just as usual. Click here for instructions on that.
2. Go to 500px.com/store and click the "Choose File" or "Change Image" link next to the photo you'd like to submit for sale.
3. Select the high resolution file, and upload it! You're all set!
Now complete the rest of the submission at 500px.com/manage!