Social media marketing (promoting an advertiser in social media) is allowed if indicated in the program terms.
When promoting an advertiser via social media or a blog it should be clear to the visitor/follower that it concerns advertising.
If this is not known (or is assumed to be known), it must be communicated. The way in which the publisher should indicate this differs from country to country. Make sure you find out before you run any promotions.
For the Netherlands this is described in the Advertising Code for Social Media. This code is part of the Dutch Advertising Code: https://www.reclamecode.nl/nrc/reclamecode-social-media-rsm/.
For Belgium, we refer you for example to the JEP: https://www.jep.be/sites/default/files/rule_reccommendation/aanbevelingen_van_de_raad_voor_de_reclame_online_influencers_nl.pdf.
For Germany, we refer you for example to the Medienanstalten: https://www.die-medienanstalten.de/fileadmin/user_upload/Rechtsgrundlagen/Richtlinien_Leitfaeden/Leitfaden_Medienanstalten_Werbekennzeichnung_Social_Media.pdf
Note: The exposure may not actively influence the buying behavior of the viewer.