Hi there, I found a free tool that I think might be useful to you:
https://www.sharelinkgenerator.com/
This can generate HTML links for you to put in your end of survey message and includes Facebook, Twitter, Linkedin, Pinterest, and Email.
The below Hubspot article goes into a bit more detail on how to work with it and also provides a link to free icons that you can use if you wanted to have respondents click the Facebook/Twitter icon to share the survey URL.
https://blog.hubspot.com/marketing/social-sharing-links-quick-tip-ht

Thanks @Tom_1842 for this. I have a follow up question. I am planning an intervention in one of my studies and want to measure sharing intention of the paricipants.
Through the link generator you shared, I am able to create link. However, I want to know (which is the real measure of the effectiveness of the intention) whether I can keep a track of the numbers of the participants who shared the particular link I wanted them to share or not.
Needless to say that I want the anonimity of the paricipants to be maintained. 

Thanks in advance.

Hi @Tom_1842, thanks for the reply. Is that any way to know the count of how many participants actually shared it on social media?