Reply To: Swatches and Attributes

Hello,

I have visited the URL you provided. If you want to add size guides to the product page then you need to create one from Dashboard >> Size Guides.

Screenshot for Clarification: https://ibb.co/wrpMm1s

Then you need to assign it to the product from the edit product.

Screenshot for Clarification: https://ibb.co/9HPtDRg

If you want to use sizes are variations then you can read the following link for further help:
https://docs.woocommerce.com/document/variable-product/

Best Regards.