How to change the size of image ?

Hello, Author, Thanks for developing such a good related image plugin, it works well with my website, but there is one thing that need your help, that is how to custom the size of image ? what is more , i have read the previous solution https://www.ads-software.com/support/topic/want-to-custom-image-size?replies=4, but i am unable to understand it , so i wish you can help me out. thanks in advance.

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