I agree with Jerome, ImageJ/FIJI would also be my first choice. However, you need the calibration data of your image, i.e. micron/pixel. With this knowledge, you could basically use any image editing software to add a line with the correct length. The calibration value is often available in the image metadata (saved with the file in e.g. OME-TIFF or separately as e.g. XML file).
If your microscope does not supply you with micron bar, I doubt very much it will have any calibration data in its files (whethere TIFFs or others). You need to make pictures of calibration standard (ruler, grid, etc.); without a standard calibration (and drawing of micron bars) is kind of a fraud.
(excerpt from Lab Math) "To create a scale bar by hand, you have to make an image of a ruler or a stage micrometer that is magnified the same amount as the image. If the image is electronic, graphics software, such as Photoshop [or ImageJ] can be used to add a line electronically; but you will still need a picture of a ruler. If you are using graphics software, you must be careful that the resolution of the image of the ruler is the same as the resolution of the image you are labeling. If it isn’t, cutting and pasting may alter the relative lengths and the scale bar will be wrong"
First you need to take an image of microscale, such as using glass micrometer scale (https://www.tedpella.com/calibration_html/Light-Microscopy-Calibration-Standards.htm#linear-glass-scales).
Then, you can use ImageJ software, to make a scale bar into your image. As Dany S Adams said, the image of micrometer scale and your image should be in the same magnification and resolution.
You can see step by step to do it, in: https://imagej.nih.gov/ij/docs/guide/user-guide.pdf,
My TEM gives a normal tif image which is also calibrated. but the Image analysis software (SiViewer, Olumpus ) does not work. Is there anyother softwares that can do the same job for adding the scale bar automatically??