See if your photo is uploaded successfully to the ssc website then there is no problem with your picture. And if your image is 28.4KB then its ok to upload it.

The point of this instruction of SSC is that, if you try to upload a image greater than the prescribed size then it will not get uploaded. There are no such cancellation or anything like that. And your image size is perfect, so you can upload it without any doubts.

TO know more about SSC GD visit the link below:

https://competition.careers360.com/exams/ssc-gd-constable

I hope this answer helps. All the very best for your future endeavors!